diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..8bb589f
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,11 @@
+.git
+.github
+*.md
+LICENSE
+examples/
+tests/
+test-email-sender/
+**/bin/
+**/obj/
+.env
+.env.*
diff --git a/.gitignore b/.gitignore
index 35ec13f..0bc623d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -308,4 +308,6 @@ $RECYCLE.BIN/
 tests/CCAI.NET.IntegrationTests/
 test_real_webhook.cs
 test-real-webhook/
-CCAI.NET.IntegrationTests
\ No newline at end of file
+CCAI.NET.IntegrationTests
+
+.claude/
diff --git a/README.md b/README.md
index 84a9e47..f59007b 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,10 @@ A C# client library for interacting with the [CloudContactAI](https://cloudconta
 - Send SMS messages to single or multiple recipients
 - Send MMS messages with images (automatic S3 upload)
 - Send Email campaigns to single or multiple recipients
+- Brand registration and management for TCR verification
+- Campaign registration and management for TCR carrier vetting
 - Manage contact opt-out preferences (SetDoNotText)
+- Validate email addresses (valid/invalid/risky) and phone numbers (valid/invalid/landline)
 - Webhook management: register, list, update, delete
 - Webhook signature verification
 - Template variable substitution (`${firstName}`, `${lastName}`)
@@ -278,6 +281,38 @@ await ccai.Contact.SetDoNotTextAsync(false, phone: "+15551234567");
 await ccai.Contact.SetDoNotTextAsync(true, contactId: "contact-abc-123");
 ```
 
+### Contact Validator
+
+Validate email addresses and phone numbers.
+
+```csharp
+using CCAI.NET;
+using CCAI.NET.ContactValidator;
+
+// Validate a single email
+var emailResult = await ccai.ContactValidator.ValidateEmailAsync("user@example.com");
+Console.WriteLine(emailResult.Status); // "valid" | "invalid" | "risky"
+
+// Validate multiple emails (up to 50)
+var bulkEmails = await ccai.ContactValidator.ValidateEmailsAsync(new[] {
+    "user@example.com",
+    "bad@invalid.xyz"
+});
+Console.WriteLine(bulkEmails.Summary.Total); // 2
+Console.WriteLine(bulkEmails.Summary.Valid);  // 1
+
+// Validate a single phone number
+var phoneResult = await ccai.ContactValidator.ValidatePhoneAsync("+15551234567", "US");
+Console.WriteLine(phoneResult.Status); // "valid" | "invalid" | "landline"
+
+// Validate multiple phone numbers (up to 50)
+var bulkPhones = await ccai.ContactValidator.ValidatePhonesAsync(new[] {
+    new PhoneInput { Phone = "+15551234567" },
+    new PhoneInput { Phone = "+15559876543", CountryCode = "US" }
+});
+Console.WriteLine(bulkPhones.Summary.Landline); // 1
+```
+
 ### Webhook Management
 
 #### CloudContact Webhook Events (New Format)
@@ -452,6 +487,139 @@ else
 }
 ```
 
+### Brand Registration
+
+Register and manage brands for TCR (The Campaign Registry) business verification.
+
+```csharp
+using CCAI.NET;
+using CCAI.NET.Brands;
+
+var ccai = new CCAIClient(new CCAIConfig
+{
+    ClientId = "YOUR-CLIENT-ID",
+    ApiKey = "YOUR-API-KEY"
+});
+
+// Create a brand
+var brand = await ccai.Brands.CreateAsync(new BrandRequest
+{
+    LegalCompanyName = "Collect.org Inc.",
+    Dba = "Collect",
+    EntityType = "NON_PROFIT",
+    TaxId = "123456789",
+    TaxIdCountry = "US",
+    Country = "US",
+    VerticalType = "NON_PROFIT",
+    WebsiteUrl = "https://www.collect.org",
+    Street = "123 Main Street",
+    City = "San Francisco",
+    State = "CA",
+    PostalCode = "94105",
+    ContactFirstName = "Jane",
+    ContactLastName = "Doe",
+    ContactEmail = "jane@collect.org",
+    ContactPhone = "+14155551234"
+});
+Console.WriteLine($"Brand created with ID: {brand.Id}");
+
+// Get a brand by ID
+var fetched = await ccai.Brands.GetAsync(brand.Id);
+Console.WriteLine($"Website match score: {fetched.WebsiteMatchScore?.ToString() ?? "pending"}");
+
+// List all brands for the account
+var brands = await ccai.Brands.ListAsync();
+Console.WriteLine($"Found {brands.Length} brand(s)");
+
+// Update a brand (partial update)
+var updated = await ccai.Brands.UpdateAsync(brand.Id, new BrandRequest
+{
+    Street = "456 Oak Avenue",
+    City = "Los Angeles"
+});
+
+// Delete a brand
+await ccai.Brands.DeleteAsync(brand.Id);
+```
+
+#### Entity Types
+
+`PRIVATE_PROFIT`, `PUBLIC_PROFIT`, `NON_PROFIT`, `GOVERNMENT`, `SOLE_PROPRIETOR`
+
+> Note: `PUBLIC_PROFIT` entities require `StockSymbol` and `StockExchange` fields.
+
+#### Vertical Types
+
+`AUTOMOTIVE`, `AGRICULTURE`, `BANKING`, `COMMUNICATION`, `CONSTRUCTION`, `EDUCATION`, `ENERGY`, `ENTERTAINMENT`, `GOVERNMENT`, `HEALTHCARE`, `HOSPITALITY`, `INSURANCE`, `LEGAL`, `MANUFACTURING`, `NON_PROFIT`, `PROFESSIONAL`, `REAL_ESTATE`, `RETAIL`, `TECHNOLOGY`, `TRANSPORTATION`
+
+### Campaign Registration
+
+Register and manage campaigns for TCR (The Campaign Registry) carrier vetting. Each campaign must be linked to a verified brand.
+
+```csharp
+using CCAI.NET;
+using CCAI.NET.Campaigns;
+
+var ccai = new CCAIClient(new CCAIConfig
+{
+    ClientId = "YOUR-CLIENT-ID",
+    ApiKey = "YOUR-API-KEY"
+});
+
+// Create a campaign
+var campaign = await ccai.Campaigns.CreateAsync(new CampaignRequest
+{
+    BrandId = 1,
+    UseCase = "MIXED",
+    SubUseCases = new List<string> { "CUSTOMER_CARE", "TWO_FACTOR_AUTHENTICATION", "ACCOUNT_NOTIFICATION" },
+    Description = "Security codes and support messaging.",
+    MessageFlow = "Users opt-in via signup form at https://example.com/signup",
+    HasEmbeddedLinks = true,
+    HasEmbeddedPhone = false,
+    IsAgeGated = false,
+    IsDirectLending = false,
+    OptInKeywords = new List<string> { "START" },
+    OptInMessage = "Welcome! Reply STOP to cancel.",
+    OptInProofUrl = "https://example.com/opt-in-proof.png",
+    HelpKeywords = new List<string> { "HELP" },
+    HelpMessage = "For HELP email support@example.com.",
+    OptOutKeywords = new List<string> { "STOP" },
+    OptOutMessage = "STOP received. You are unsubscribed.",
+    SampleMessages = new List<string>
+    {
+        "Your code is 554321. Reply STOP to cancel.",
+        "Your ticket has been updated. Reply HELP for info."
+    }
+});
+Console.WriteLine($"Campaign created with ID: {campaign.Id}");
+
+// Get a campaign by ID
+var fetched = await ccai.Campaigns.GetAsync(campaign.Id);
+
+// List all campaigns for the account
+var campaigns = await ccai.Campaigns.ListAsync();
+Console.WriteLine($"Found {campaigns.Length} campaign(s)");
+
+// Update a campaign (partial update)
+var updated = await ccai.Campaigns.UpdateAsync(campaign.Id, new CampaignRequest
+{
+    Description = "Updated description."
+});
+
+// Delete a campaign
+await ccai.Campaigns.DeleteAsync(campaign.Id);
+```
+
+#### Use Cases
+
+`TWO_FACTOR_AUTHENTICATION`, `ACCOUNT_NOTIFICATION`, `CUSTOMER_CARE`, `DELIVERY_NOTIFICATION`, `FRAUD_ALERT`, `HIGHER_EDUCATION`, `LOW_VOLUME_MIXED`, `MARKETING`, `MIXED`, `POLLING_VOTING`, `PUBLIC_SERVICE_ANNOUNCEMENT`, `SECURITY_ALERT`
+
+> Note: `MIXED` and `LOW_VOLUME_MIXED` campaigns require 2–3 `SubUseCases`.
+
+#### Sub-Use Cases
+
+`TWO_FACTOR_AUTHENTICATION`, `ACCOUNT_NOTIFICATION`, `CUSTOMER_CARE`, `DELIVERY_NOTIFICATION`, `FRAUD_ALERT`, `MARKETING`, `POLLING_VOTING`
+
 ### Step-by-Step MMS Workflow
 
 ```csharp
diff --git a/RELEASE-NOTES-v1.5.0.md b/RELEASE-NOTES-v1.5.0.md
new file mode 100644
index 0000000..5daddd0
--- /dev/null
+++ b/RELEASE-NOTES-v1.5.0.md
@@ -0,0 +1,10 @@
+# Release Notes - Version 1.5.0
+
+## New Features
+- Added `ContactValidator` service for validating email addresses and phone numbers
+- `ValidateEmailAsync` / `ValidateEmail` — validate a single email, returns `valid`, `invalid`, or `risky` status with `safe_to_send` and `ai_verdict` metadata
+- `ValidateEmailsAsync` / `ValidateEmails` — bulk email validation (up to 50 addresses) with summary counts
+- `ValidatePhoneAsync` / `ValidatePhone` — validate a single phone number, returns `valid`, `invalid`, or `landline` status with carrier metadata
+- `ValidatePhonesAsync` / `ValidatePhones` — bulk phone validation (up to 50 numbers) with summary counts including landline count
+- New models: `EmailValidationResult`, `PhoneValidationResult`, `ValidationSummary`, `BulkEmailValidationResult`, `BulkPhoneValidationResult`, `PhoneInput`
+- `IContactValidatorService` interface for dependency injection and testing
diff --git a/examples/BrandExample.cs b/examples/BrandExample.cs
new file mode 100644
index 0000000..9c0b72e
--- /dev/null
+++ b/examples/BrandExample.cs
@@ -0,0 +1,88 @@
+// Copyright (c) 2025 CloudContactAI LLC
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using System;
+using System.Threading.Tasks;
+using CCAI.NET;
+using CCAI.NET.Brands;
+using DotNetEnv;
+
+namespace CCAI.NET.Examples;
+
+/// <summary>
+/// Brand registration example using the CCAI.NET client
+/// </summary>
+public class BrandExample
+{
+    public static async Task RunAsync()
+    {
+        Env.Load("./.env");
+
+        var config = new CCAIConfig
+        {
+            ClientId = Environment.GetEnvironmentVariable("CCAI_CLIENT_ID") ??
+                      throw new InvalidOperationException("CCAI_CLIENT_ID not found"),
+            ApiKey = Environment.GetEnvironmentVariable("CCAI_API_KEY") ??
+                    throw new InvalidOperationException("CCAI_API_KEY not found"),
+            UseTestEnvironment = true
+        };
+
+        using var ccai = new CCAIClient(config);
+
+        try
+        {
+            // Create a brand
+            Console.WriteLine("Creating a brand...");
+            var brand = await ccai.Brands.CreateAsync(new BrandRequest
+            {
+                LegalCompanyName = "Collect.org Inc.",
+                Dba = "Collect",
+                EntityType = "NON_PROFIT",
+                TaxId = "123456789",
+                TaxIdCountry = "US",
+                Country = "US",
+                VerticalType = "NON_PROFIT",
+                WebsiteUrl = "https://www.collect.org",
+                Street = "123 Main Street",
+                City = "San Francisco",
+                State = "CA",
+                PostalCode = "94105",
+                ContactFirstName = "Jane",
+                ContactLastName = "Doe",
+                ContactEmail = "jane@collect.org",
+                ContactPhone = "+14155551234"
+            });
+            Console.WriteLine($"Brand created with ID: {brand.Id}");
+
+            // Get brand by ID
+            Console.WriteLine("\nFetching brand by ID...");
+            var fetched = await ccai.Brands.GetAsync(brand.Id);
+            Console.WriteLine($"Brand: {fetched.LegalCompanyName}, Score: {fetched.WebsiteMatchScore?.ToString() ?? "pending"}");
+
+            // List all brands
+            Console.WriteLine("\nListing all brands...");
+            var brands = await ccai.Brands.ListAsync();
+            Console.WriteLine($"Found {brands.Length} brand(s)");
+
+            // Update a brand
+            Console.WriteLine("\nUpdating brand...");
+            var updated = await ccai.Brands.UpdateAsync(brand.Id, new BrandRequest
+            {
+                Street = "456 Oak Avenue",
+                City = "Los Angeles",
+                ContactEmail = "admin@collect.org"
+            });
+            Console.WriteLine($"Brand updated: {updated.Street}, {updated.City}");
+
+            // Delete a brand
+            Console.WriteLine("\nDeleting brand...");
+            await ccai.Brands.DeleteAsync(brand.Id);
+            Console.WriteLine("Brand deleted successfully");
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine($"Error: {ex.Message}");
+            throw;
+        }
+    }
+}
diff --git a/examples/CampaignExample.cs b/examples/CampaignExample.cs
new file mode 100644
index 0000000..bead8d8
--- /dev/null
+++ b/examples/CampaignExample.cs
@@ -0,0 +1,100 @@
+// Copyright (c) 2025 CloudContactAI LLC
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using CCAI.NET;
+using CCAI.NET.Campaigns;
+using DotNetEnv;
+
+namespace CCAI.NET.Examples;
+
+/// <summary>
+/// Campaign registration example using the CCAI.NET client
+/// </summary>
+public class CampaignExample
+{
+    public static async Task RunAsync()
+    {
+        Env.Load("./.env");
+
+        var config = new CCAIConfig
+        {
+            ClientId = Environment.GetEnvironmentVariable("CCAI_CLIENT_ID") ??
+                      throw new InvalidOperationException("CCAI_CLIENT_ID not found"),
+            ApiKey = Environment.GetEnvironmentVariable("CCAI_API_KEY") ??
+                    throw new InvalidOperationException("CCAI_API_KEY not found"),
+            UseTestEnvironment = true
+        };
+
+        using var ccai = new CCAIClient(config);
+
+        try
+        {
+            // Create a campaign (assumes brand ID 1 exists)
+            Console.WriteLine("Creating a campaign...");
+            var campaign = await ccai.Campaigns.CreateAsync(new CampaignRequest
+            {
+                BrandId = 1,
+                UseCase = "MIXED",
+                SubUseCases = new List<string> { "CUSTOMER_CARE", "TWO_FACTOR_AUTHENTICATION", "ACCOUNT_NOTIFICATION" },
+                Description = "This campaign handles security codes and support for Collect.org.",
+                MessageFlow = "Users opt-in via our signup form checkbox at https://collect.org/signup",
+                TermsLink = "https://collect.org/terms",
+                PrivacyLink = "https://collect.org/privacy",
+                HasEmbeddedLinks = true,
+                HasEmbeddedPhone = false,
+                IsAgeGated = false,
+                IsDirectLending = false,
+                OptInKeywords = new List<string> { "START", "JOIN" },
+                OptInMessage = "Welcome to Collect.org! Msg&Data rates may apply. Reply STOP to cancel.",
+                OptInProofUrl = "https://collect.org/images/opt-in-proof.png",
+                HelpKeywords = new List<string> { "HELP", "INFO" },
+                HelpMessage = "Collect.org: For help email support@collect.org. Reply STOP to cancel.",
+                OptOutKeywords = new List<string> { "STOP", "UNSUBSCRIBE" },
+                OptOutMessage = "Collect.org: You have been unsubscribed. STOP received.",
+                SampleMessages = new List<string>
+                {
+                    "Your Collect.org security code is 554321. Reply STOP to cancel.",
+                    "Hi [Name], your ticket #[ID] has been updated. Reply HELP for more info."
+                }
+            });
+            Console.WriteLine($"Campaign created with ID: {campaign.Id}, fee: ${campaign.MonthlyFee}/mo");
+
+            // Get campaign by ID
+            Console.WriteLine("\nFetching campaign by ID...");
+            var fetched = await ccai.Campaigns.GetAsync(campaign.Id);
+            Console.WriteLine($"Campaign: {fetched.UseCase}, Brand: {fetched.BrandId}");
+
+            // List all campaigns
+            Console.WriteLine("\nListing all campaigns...");
+            var campaigns = await ccai.Campaigns.ListAsync();
+            Console.WriteLine($"Found {campaigns.Length} campaign(s)");
+
+            // Update a campaign
+            Console.WriteLine("\nUpdating campaign...");
+            var updated = await ccai.Campaigns.UpdateAsync(campaign.Id, new CampaignRequest
+            {
+                Description = "Updated campaign description for Collect.org messaging.",
+                SampleMessages = new List<string>
+                {
+                    "Your Collect.org code is 123456. Reply STOP to opt-out.",
+                    "Your support ticket has been resolved. Reply HELP for more info.",
+                    "Your payment of $50.00 was received. Reply STOP to cancel."
+                }
+            });
+            Console.WriteLine($"Campaign updated: {updated.Description}");
+
+            // Delete a campaign
+            Console.WriteLine("\nDeleting campaign...");
+            await ccai.Campaigns.DeleteAsync(campaign.Id);
+            Console.WriteLine("Campaign deleted successfully");
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine($"Error: {ex.Message}");
+            throw;
+        }
+    }
+}
diff --git a/integration/CCAITest.csproj b/integration/CCAITest.csproj
new file mode 100644
index 0000000..4527319
--- /dev/null
+++ b/integration/CCAITest.csproj
@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <AssemblyName>CCAITest</AssemblyName>
+  </PropertyGroup>
+
+  <!-- SDK is always the parent directory (integration/ lives inside the SDK repo) -->
+  <ItemGroup>
+    <ProjectReference Include="$(MSBuildThisFileDirectory)..\src\CCAI.NET\CCAI.NET.csproj" />
+  </ItemGroup>
+
+</Project>
diff --git a/integration/Dockerfile b/integration/Dockerfile
new file mode 100644
index 0000000..b885c33
--- /dev/null
+++ b/integration/Dockerfile
@@ -0,0 +1,16 @@
+FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+
+WORKDIR /sdk
+COPY src/CCAI.NET/CCAI.NET.csproj ./src/CCAI.NET/
+COPY integration/CCAITest.csproj ./integration/
+RUN echo "" > RELEASE-NOTES-v1.4.5.md
+RUN dotnet restore ./integration/CCAITest.csproj
+
+COPY src/ ./src/
+COPY integration/ ./integration/
+RUN dotnet build ./integration/CCAITest.csproj -c Release -o /app/out -p:GeneratePackageOnBuild=false
+
+FROM mcr.microsoft.com/dotnet/runtime:8.0
+WORKDIR /app
+COPY --from=build /app/out ./
+CMD ["dotnet", "CCAITest.dll"]
diff --git a/integration/Program.cs b/integration/Program.cs
new file mode 100644
index 0000000..8d6670c
--- /dev/null
+++ b/integration/Program.cs
@@ -0,0 +1,631 @@
+// .NET SDK integration tests — 42 tests
+// Covers: SMS (1-6), MMS (7-17), Email (18-22), Webhook (23-29), Contact (30-31), Brands (32-36), Campaigns (37-42)
+
+using System.Security.Cryptography;
+using System.Text;
+using System.Text.Json;
+using CCAI.NET;
+using CCAI.NET.Brands;
+using CCAI.NET.Campaigns;
+using CCAI.NET.Email;
+using CCAI.NET.SMS;
+using CCAI.NET.Webhook;
+using CCAI.NET.ContactValidator;
+
+int passed = 0;
+int failed = 0;
+
+// ── Helpers ───────────────────────────────────────────────────────────────────
+
+async Task Run(string name, Func<Task> fn)
+{
+    try
+    {
+        await fn();
+        Console.WriteLine($"  PASS [{name}]");
+        passed++;
+    }
+    catch (Exception ex)
+    {
+        Console.WriteLine($"  FAIL [{name}]: {ex.Message}");
+        failed++;
+    }
+}
+
+string MustEnv(string key)
+{
+    var val = Environment.GetEnvironmentVariable(key);
+    if (string.IsNullOrEmpty(val))
+    {
+        Console.Error.WriteLine($"ERROR: required env var {key} is not set");
+        Environment.Exit(2);
+    }
+    return val!;
+}
+
+string HmacSha256Base64(string secret, string message)
+{
+    using var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(secret));
+    var hash = hmac.ComputeHash(Encoding.UTF8.GetBytes(message));
+    return Convert.ToBase64String(hash);
+}
+
+string WriteTempPng()
+{
+    var pngB64 = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwADhQGAWjR9awAAAABJRU5ErkJggg==";
+    var buf = Convert.FromBase64String(pngB64);
+    var path = Path.Combine(Path.GetTempPath(), $"ccai_test_{DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()}.png");
+    File.WriteAllBytes(path, buf);
+    return path;
+}
+
+// ── Setup ─────────────────────────────────────────────────────────────────────
+
+var clientId  = MustEnv("CCAI_CLIENT_ID");
+var apiKey    = MustEnv("CCAI_API_KEY");
+var phone1    = MustEnv("CCAI_TEST_PHONE");
+var phone2    = MustEnv("CCAI_TEST_PHONE_2");
+var phone3    = MustEnv("CCAI_TEST_PHONE_3");
+var email1    = MustEnv("CCAI_TEST_EMAIL");
+var email2    = MustEnv("CCAI_TEST_EMAIL_2");
+var email3    = MustEnv("CCAI_TEST_EMAIL_3");
+var fn1       = MustEnv("CCAI_TEST_FIRST_NAME");
+var ln1       = MustEnv("CCAI_TEST_LAST_NAME");
+var fn2       = MustEnv("CCAI_TEST_FIRST_NAME_2");
+var ln2       = MustEnv("CCAI_TEST_LAST_NAME_2");
+var fn3       = MustEnv("CCAI_TEST_FIRST_NAME_3");
+var ln3       = MustEnv("CCAI_TEST_LAST_NAME_3");
+var webhookUrl = MustEnv("WEBHOOK_URL");
+
+// Use CCAI_BASE_URL if set (local dev), otherwise fall back to test environment
+var client = new CCAIClient(new CCAIConfig
+{
+    ClientId = clientId,
+    ApiKey = apiKey,
+    UseTestEnvironment = Environment.GetEnvironmentVariable("CCAI_BASE_URL") is null
+});
+
+var pngPath = WriteTempPng();
+
+Console.WriteLine("==============================================");
+Console.WriteLine("  CCAI .NET SDK Integration Tests");
+Console.WriteLine("==============================================");
+
+// ── SMS Tests (1-6) ───────────────────────────────────────────────────────────
+Console.WriteLine("\n--- SMS ---");
+
+// 01 — SMS.SendSingleAsync
+await Run("01 SMS.SendSingleAsync", async () =>
+{
+    await client.SMS.SendSingleAsync(fn1, ln1, phone1, "Hello from .NET SDK!", ".NET Test");
+});
+
+// 02 — SMS.SendAsync (1 recipient)
+await Run("02 SMS.SendAsync (1 recipient)", async () =>
+{
+    await client.SMS.SendAsync(
+        [new Account { FirstName = fn1, LastName = ln1, Phone = phone1 }],
+        "Hello 1 recipient!", ".NET Test");
+});
+
+// 03 — SMS.SendAsync (2 recipients)
+await Run("03 SMS.SendAsync (2 recipients)", async () =>
+{
+    await client.SMS.SendAsync(
+        [
+            new Account { FirstName = fn1, LastName = ln1, Phone = phone1 },
+            new Account { FirstName = fn2, LastName = ln2, Phone = phone2 },
+        ],
+        "Hello 2 recipients!", ".NET Test");
+});
+
+// 04 — SMS.SendAsync (3 recipients)
+await Run("04 SMS.SendAsync (3 recipients)", async () =>
+{
+    await client.SMS.SendAsync(
+        [
+            new Account { FirstName = fn1, LastName = ln1, Phone = phone1 },
+            new Account { FirstName = fn2, LastName = ln2, Phone = phone2 },
+            new Account { FirstName = fn3, LastName = ln3, Phone = phone3 },
+        ],
+        "Hello 3 recipients!", ".NET Test");
+});
+
+// 05 — SMS.SendAsync with Data
+await Run("05 SMS.SendAsync with Data", async () =>
+{
+    await client.SMS.SendAsync(
+        [new Account { FirstName = fn1, LastName = ln1, Phone = phone1, Data = new() { ["city"] = "Miami", ["offer"] = "20% off" } }],
+        "Hello from ${city}! Claim your ${offer}.", ".NET Test Data");
+});
+
+// 06 — SMS.SendAsync with CustomData
+await Run("06 SMS.SendAsync with CustomData", async () =>
+{
+    await client.SMS.SendAsync(
+        [new Account { FirstName = fn1, LastName = ln1, Phone = phone1, CustomData = "{\"trackingId\":\"abc123\"}" }],
+        "Hello with messageData!", ".NET Test MsgData");
+});
+
+// ── MMS Tests (7-17) ──────────────────────────────────────────────────────────
+Console.WriteLine("\n--- MMS ---");
+
+SignedUrlResponse? signedUrlResp = null;
+bool mmsDep = false;
+
+// 07 — MMS.GetSignedUploadUrlAsync
+await Run("07 MMS.GetSignedUploadUrlAsync", async () =>
+{
+    var resp = await client.MMS.GetSignedUploadUrlAsync("test_image.png", "image/png");
+    if (string.IsNullOrEmpty(resp.SignedS3Url))
+    {
+        mmsDep = true;
+        throw new Exception("SignedS3Url is empty");
+    }
+    signedUrlResp = resp;
+});
+
+// 08 — MMS.UploadImageToSignedUrlAsync
+await Run("08 MMS.UploadImageToSignedUrlAsync", async () =>
+{
+    if (mmsDep || signedUrlResp == null) throw new Exception("dependency test 07 failed");
+    var ok = await client.MMS.UploadImageToSignedUrlAsync(signedUrlResp.SignedS3Url, pngPath, "image/png");
+    if (!ok) throw new Exception("upload returned false");
+});
+
+// 09 — MMS.SendSingleAsync
+await Run("09 MMS.SendSingleAsync", async () =>
+{
+    if (mmsDep || signedUrlResp == null) throw new Exception("dependency test 07 failed");
+    await client.MMS.SendSingleAsync(signedUrlResp.FileKey, fn1, ln1, phone1, "MMS single!", ".NET MMS Test");
+});
+
+// 10 — MMS.SendAsync (1 recipient)
+await Run("10 MMS.SendAsync (1 recipient)", async () =>
+{
+    if (mmsDep || signedUrlResp == null) throw new Exception("dependency test 07 failed");
+    await client.MMS.SendAsync(signedUrlResp.FileKey,
+        [new Account { FirstName = fn1, LastName = ln1, Phone = phone1 }],
+        "MMS 1 recipient!", ".NET MMS Test");
+});
+
+// 11 — MMS.SendAsync (2 recipients)
+await Run("11 MMS.SendAsync (2 recipients)", async () =>
+{
+    if (mmsDep || signedUrlResp == null) throw new Exception("dependency test 07 failed");
+    await client.MMS.SendAsync(signedUrlResp.FileKey,
+        [
+            new Account { FirstName = fn1, LastName = ln1, Phone = phone1 },
+            new Account { FirstName = fn2, LastName = ln2, Phone = phone2 },
+        ],
+        "MMS 2 recipients!", ".NET MMS Test");
+});
+
+// 12 — MMS.SendAsync (3 recipients)
+await Run("12 MMS.SendAsync (3 recipients)", async () =>
+{
+    if (mmsDep || signedUrlResp == null) throw new Exception("dependency test 07 failed");
+    await client.MMS.SendAsync(signedUrlResp.FileKey,
+        [
+            new Account { FirstName = fn1, LastName = ln1, Phone = phone1 },
+            new Account { FirstName = fn2, LastName = ln2, Phone = phone2 },
+            new Account { FirstName = fn3, LastName = ln3, Phone = phone3 },
+        ],
+        "MMS 3 recipients!", ".NET MMS Test");
+});
+
+// 13 — MMS.SendAsync with Data
+await Run("13 MMS.SendAsync with Data", async () =>
+{
+    if (mmsDep || signedUrlResp == null) throw new Exception("dependency test 07 failed");
+    await client.MMS.SendAsync(signedUrlResp.FileKey,
+        [new Account { FirstName = fn1, LastName = ln1, Phone = phone1, Data = new() { ["product"] = "Widget" } }],
+        "Check out ${product}!", ".NET MMS Data");
+});
+
+// 14 — MMS.SendAsync with CustomData
+await Run("14 MMS.SendAsync with CustomData", async () =>
+{
+    if (mmsDep || signedUrlResp == null) throw new Exception("dependency test 07 failed");
+    await client.MMS.SendAsync(signedUrlResp.FileKey,
+        [new Account { FirstName = fn1, LastName = ln1, Phone = phone1, CustomData = "{\"campaignId\":\"mms-net-001\"}" }],
+        "MMS with messageData!", ".NET MMS MsgData");
+});
+
+// 15 — MMS.CheckFileUploadedAsync
+await Run("15 MMS.CheckFileUploadedAsync", async () =>
+{
+    if (mmsDep || signedUrlResp == null) throw new Exception("dependency test 07 failed");
+    await client.MMS.CheckFileUploadedAsync(signedUrlResp.FileKey);
+});
+
+// 16 — MMS.SendWithImageAsync (fresh upload)
+await Run("16 MMS.SendWithImageAsync (fresh upload)", async () =>
+{
+    if (mmsDep) throw new Exception("dependency test 07 failed");
+    await client.MMS.SendWithImageAsync(pngPath, "image/png",
+        [new Account { FirstName = fn1, LastName = ln1, Phone = phone1 }],
+        "MMS with image!", ".NET MMS Image",
+        forceNewCampaign: true);
+});
+
+// 17 — MMS.SendWithImageAsync (cached)
+await Run("17 MMS.SendWithImageAsync (cached)", async () =>
+{
+    if (mmsDep) throw new Exception("dependency test 07 failed");
+    await client.MMS.SendWithImageAsync(pngPath, "image/png",
+        [new Account { FirstName = fn1, LastName = ln1, Phone = phone1 }],
+        "MMS cached image!", ".NET MMS Cache",
+        forceNewCampaign: true);
+});
+
+// ── Email Tests (18-22) ───────────────────────────────────────────────────────
+Console.WriteLine("\n--- Email ---");
+
+const string SenderEmail = "noreply@cloudcontactai.com";
+const string SenderName  = "CCAI Test";
+const string ReplyEmail  = "noreply@cloudcontactai.com";
+
+// 18 — Email.SendSingleAsync
+await Run("18 Email.SendSingleAsync", async () =>
+{
+    await client.Email.SendSingleAsync(
+        fn1, ln1, email1,
+        ".NET SDK Test Email", "<p>Hello from .NET SDK!</p>",
+        senderEmail: SenderEmail, replyEmail: ReplyEmail, senderName: SenderName,
+        title: ".NET Email Test");
+});
+
+// 19 — Email.SendCampaignAsync (1 recipient)
+await Run("19 Email.SendCampaignAsync (1 recipient)", async () =>
+{
+    await client.Email.SendCampaignAsync(new EmailCampaign
+    {
+        Subject = ".NET SDK Email 1",
+        Title = ".NET Email Test",
+        Message = "<p>Hello 1!</p>",
+        SenderEmail = SenderEmail, ReplyEmail = ReplyEmail, SenderName = SenderName,
+        Accounts = [new EmailAccount { FirstName = fn1, LastName = ln1, Email = email1 }]
+    });
+});
+
+// 20 — Email.SendCampaignAsync (2 recipients)
+await Run("20 Email.SendCampaignAsync (2 recipients)", async () =>
+{
+    await client.Email.SendCampaignAsync(new EmailCampaign
+    {
+        Subject = ".NET SDK Email 2",
+        Title = ".NET Email Test",
+        Message = "<p>Hello 2!</p>",
+        SenderEmail = SenderEmail, ReplyEmail = ReplyEmail, SenderName = SenderName,
+        Accounts =
+        [
+            new EmailAccount { FirstName = fn1, LastName = ln1, Email = email1 },
+            new EmailAccount { FirstName = fn2, LastName = ln2, Email = email2 },
+        ]
+    });
+});
+
+// 21 — Email.SendCampaignAsync (3 recipients)
+await Run("21 Email.SendCampaignAsync (3 recipients)", async () =>
+{
+    await client.Email.SendCampaignAsync(new EmailCampaign
+    {
+        Subject = ".NET SDK Email 3",
+        Title = ".NET Email Test",
+        Message = "<p>Hello 3!</p>",
+        SenderEmail = SenderEmail, ReplyEmail = ReplyEmail, SenderName = SenderName,
+        Accounts =
+        [
+            new EmailAccount { FirstName = fn1, LastName = ln1, Email = email1 },
+            new EmailAccount { FirstName = fn2, LastName = ln2, Email = email2 },
+            new EmailAccount { FirstName = fn3, LastName = ln3, Email = email3 },
+        ]
+    });
+});
+
+// 22 — Email.SendCampaignAsync (full campaign object)
+await Run("22 Email.SendCampaignAsync (full campaign)", async () =>
+{
+    await client.Email.SendCampaignAsync(new EmailCampaign
+    {
+        Subject = ".NET SDK Campaign Test",
+        Title = ".NET Email Campaign",
+        Message = "<p>Campaign email from .NET SDK!</p>",
+        SenderEmail = SenderEmail, ReplyEmail = ReplyEmail, SenderName = SenderName,
+        Accounts =
+        [
+            new EmailAccount { FirstName = fn1, LastName = ln1, Email = email1 },
+            new EmailAccount { FirstName = fn2, LastName = ln2, Email = email2 },
+        ]
+    });
+});
+
+// ── Webhook Tests (23-29) ─────────────────────────────────────────────────────
+Console.WriteLine("\n--- Webhook ---");
+
+const string WebhookSecret = "test-webhook-secret-dotnet";
+int registeredWebhookId = 0;
+
+// 23 — Webhook.RegisterAsync
+await Run("23 Webhook.RegisterAsync", async () =>
+{
+    var resp = await client.Webhook.RegisterAsync(new WebhookConfig
+    {
+        Url = webhookUrl,
+        Secret = WebhookSecret
+    });
+
+    if (resp.Id == 0) throw new Exception("webhook ID is 0 after register");
+    registeredWebhookId = resp.Id;
+});
+
+// 24 — Webhook.ListAsync
+await Run("24 Webhook.ListAsync", async () =>
+{
+    var hooks = await client.Webhook.ListAsync();
+    if (hooks == null || hooks.Count == 0) throw new Exception("expected at least one webhook, got 0");
+});
+
+// 25 — Webhook.UpdateAsync
+await Run("25 Webhook.UpdateAsync", async () =>
+{
+    if (registeredWebhookId == 0) throw new Exception("no webhook ID from test 23");
+    await client.Webhook.UpdateAsync(registeredWebhookId, new WebhookConfig
+    {
+        Url = webhookUrl + "?updated=1",
+        Secret = "updated-secret-dotnet"
+    });
+});
+
+// 26 — Webhook.VerifySignature (valid)
+await Run("26 Webhook.VerifySignature (valid)", async () =>
+{
+    await Task.CompletedTask;
+    const string eventHash = "abc123eventHash";
+    var sig = HmacSha256Base64(WebhookSecret, $"{clientId}:{eventHash}");
+    var ok = client.Webhook.VerifySignature(sig, clientId, eventHash, WebhookSecret);
+    if (!ok) throw new Exception("expected valid signature to return true");
+});
+
+// 27 — Webhook.VerifySignature (invalid)
+await Run("27 Webhook.VerifySignature (invalid)", async () =>
+{
+    await Task.CompletedTask;
+    var ok = client.Webhook.VerifySignature("invalidsig==", clientId, "somehash", WebhookSecret);
+    if (ok) throw new Exception("expected invalid signature to return false");
+});
+
+// 28 — Webhook.ParseCloudContactEvent
+await Run("28 Webhook.ParseCloudContactEvent", async () =>
+{
+    await Task.CompletedTask;
+    var payload = "{\"eventType\":\"message.sent\",\"data\":{\"To\":\"+15005550001\",\"Message\":\"test\",\"MessageStatus\":\"DELIVERED\",\"SmsSid\":1,\"CampaignId\":0,\"CampaignTitle\":\"\",\"CustomData\":\"\",\"ClientExternalId\":\"\"}}";
+    var evt = client.Webhook.ParseCloudContactEvent(payload);
+    if (string.IsNullOrEmpty(evt.EventType)) throw new Exception("EventType is empty after ParseCloudContactEvent");
+});
+
+// 29 — Webhook.DeleteAsync
+await Run("29 Webhook.DeleteAsync", async () =>
+{
+    if (registeredWebhookId == 0) throw new Exception("no webhook ID from test 23");
+    await client.Webhook.DeleteAsync(registeredWebhookId);
+});
+
+// ── Contact Tests (30-31) ─────────────────────────────────────────────────────
+Console.WriteLine("\n--- Contact ---");
+
+// 30 — Contact.SetDoNotTextAsync(true)
+await Run("30 Contact.SetDoNotTextAsync(true)", async () =>
+{
+    await client.Contact.SetDoNotTextAsync(true, phone: phone1);
+});
+
+// 31 — Contact.SetDoNotTextAsync(false)
+await Run("31 Contact.SetDoNotTextAsync(false)", async () =>
+{
+    await client.Contact.SetDoNotTextAsync(false, phone: phone1);
+});
+
+// ── Brand Tests (32-36) ───────────────────────────────────────────────────────
+Console.WriteLine("\n--- Brands ---");
+
+long brandId = 0;
+
+// 32 — Brand.CreateAsync
+await Run("32 Brand.CreateAsync", async () =>
+{
+    var resp = await client.Brands.CreateAsync(new BrandRequest
+    {
+        LegalCompanyName = "Test Company LLC",
+        EntityType       = "PRIVATE_PROFIT",
+        TaxId            = "123456789",
+        TaxIdCountry     = "US",
+        Country          = "US",
+        VerticalType     = "TECHNOLOGY",
+        WebsiteUrl       = "https://example.com",
+        Street           = "123 Main St",
+        City             = "Miami",
+        State            = "FL",
+        PostalCode       = "33101",
+        ContactFirstName = fn1,
+        ContactLastName  = ln1,
+        ContactEmail     = email1,
+        ContactPhone     = phone1
+    });
+    if (resp.Id == 0) throw new Exception("Invalid brand id");
+    brandId = resp.Id;
+});
+
+// 33 — Brand.GetAsync
+await Run("33 Brand.GetAsync", async () =>
+{
+    if (brandId == 0) throw new Exception("dependency test 32 failed");
+    var resp = await client.Brands.GetAsync(brandId);
+    if (resp.Id != brandId) throw new Exception("Brand id mismatch");
+});
+
+// 34 — Brand.ListAsync
+await Run("34 Brand.ListAsync", async () =>
+{
+    var list = await client.Brands.ListAsync();
+    if (list == null) throw new Exception("Null response");
+});
+
+// 35 — Brand.UpdateAsync
+await Run("35 Brand.UpdateAsync", async () =>
+{
+    if (brandId == 0) throw new Exception("dependency test 32 failed");
+    var resp = await client.Brands.UpdateAsync(brandId, new BrandRequest { City = "Orlando" });
+    if (resp.Id != brandId) throw new Exception("Brand id mismatch after update");
+});
+
+// 36 — Brand.DeleteAsync
+await Run("36 Brand.DeleteAsync", async () =>
+{
+    if (brandId == 0) throw new Exception("dependency test 32 failed");
+    await client.Brands.DeleteAsync(brandId);
+});
+
+// ── Campaign Tests (37-42) ────────────────────────────────────────────────────
+Console.WriteLine("\n--- Campaigns ---");
+
+long campaignBrandId = 0;
+long campaignId = 0;
+
+// 37 — Campaign setup: create brand
+await Run("37 Campaign setup — Brand.CreateAsync", async () =>
+{
+    var resp = await client.Brands.CreateAsync(new BrandRequest
+    {
+        LegalCompanyName = "Campaign Test LLC",
+        EntityType       = "PRIVATE_PROFIT",
+        TaxId            = "987654321",
+        TaxIdCountry     = "US",
+        Country          = "US",
+        VerticalType     = "TECHNOLOGY",
+        WebsiteUrl       = "https://example.com",
+        Street           = "456 Test Ave",
+        City             = "Miami",
+        State            = "FL",
+        PostalCode       = "33101",
+        ContactFirstName = fn1,
+        ContactLastName  = ln1,
+        ContactEmail     = email1,
+        ContactPhone     = phone1
+    });
+    if (resp.Id == 0) throw new Exception("Invalid brand id");
+    campaignBrandId = resp.Id;
+});
+
+// 38 — Campaign.CreateAsync
+await Run("38 Campaign.CreateAsync", async () =>
+{
+    if (campaignBrandId == 0) throw new Exception("dependency test 37 failed");
+    var resp = await client.Campaigns.CreateAsync(new CampaignRequest
+    {
+        BrandId          = campaignBrandId,
+        UseCase          = "MARKETING",
+        Description      = "Integration test campaign for automated testing",
+        MessageFlow      = "Customers opt-in via website form at https://example.com/sms-signup",
+        HasEmbeddedLinks = false,
+        HasEmbeddedPhone = false,
+        IsAgeGated       = false,
+        IsDirectLending  = false,
+        OptInKeywords    = ["START", "YES"],
+        OptInMessage     = "You have opted in to receive messages. Reply STOP to unsubscribe.",
+        OptInProofUrl    = "https://example.com/opt-in-proof",
+        HelpKeywords     = ["HELP", "INFO"],
+        HelpMessage      = "For help reply HELP or call 1-800-555-0000.",
+        OptOutKeywords   = ["STOP", "END"],
+        OptOutMessage    = "You have been unsubscribed. Reply START to opt back in. STOP",
+        SampleMessages   =
+        [
+            "Hello ${firstName}, this is a test message. Reply STOP to unsubscribe.",
+            "Reminder: your appointment is tomorrow. Reply HELP for assistance."
+        ]
+    });
+    if (resp.Id == 0) throw new Exception("Invalid campaign id");
+    campaignId = resp.Id;
+});
+
+// 39 — Campaign.GetAsync
+await Run("39 Campaign.GetAsync", async () =>
+{
+    if (campaignId == 0) throw new Exception("dependency test 38 failed");
+    var resp = await client.Campaigns.GetAsync(campaignId);
+    if (resp.Id != campaignId) throw new Exception("Campaign id mismatch");
+});
+
+// 40 — Campaign.ListAsync
+await Run("40 Campaign.ListAsync", async () =>
+{
+    var list = await client.Campaigns.ListAsync();
+    if (list == null) throw new Exception("Null response");
+});
+
+// 41 — Campaign.UpdateAsync
+await Run("41 Campaign.UpdateAsync", async () =>
+{
+    if (campaignId == 0) throw new Exception("dependency test 38 failed");
+    var resp = await client.Campaigns.UpdateAsync(campaignId, new CampaignRequest
+    {
+        Description = "Updated integration test campaign description"
+    });
+    if (resp.Id != campaignId) throw new Exception("Campaign id mismatch after update");
+});
+
+// 42 — Campaign.DeleteAsync + cleanup brand
+await Run("42 Campaign.DeleteAsync", async () =>
+{
+    if (campaignId == 0) throw new Exception("dependency test 38 failed");
+    await client.Campaigns.DeleteAsync(campaignId);
+    if (campaignBrandId != 0) await client.Brands.DeleteAsync(campaignBrandId);
+});
+
+// ── Contact Validator ──────────────────────────────────────────────────────────
+
+// 43 — ContactValidator.ValidateEmailAsync
+await Run("43 ContactValidator.ValidateEmailAsync", async () =>
+{
+    var resp = await client.ContactValidator.ValidateEmailAsync(email1);
+    if (string.IsNullOrEmpty(resp.Status)) throw new Exception("status is empty");
+});
+
+// 44 — ContactValidator.ValidateEmailsAsync
+await Run("44 ContactValidator.ValidateEmailsAsync", async () =>
+{
+    var resp = await client.ContactValidator.ValidateEmailsAsync(new[] { email1, email2 });
+    if (resp.Summary.Total != 2) throw new Exception($"expected summary.total=2, got {resp.Summary.Total}");
+});
+
+// 45 — ContactValidator.ValidatePhoneAsync
+await Run("45 ContactValidator.ValidatePhoneAsync", async () =>
+{
+    var resp = await client.ContactValidator.ValidatePhoneAsync(phone1);
+    if (string.IsNullOrEmpty(resp.Status)) throw new Exception("status is empty");
+});
+
+// 46 — ContactValidator.ValidatePhonesAsync
+await Run("46 ContactValidator.ValidatePhonesAsync", async () =>
+{
+    var resp = await client.ContactValidator.ValidatePhonesAsync(new[]
+    {
+        new PhoneInput { Phone = phone1 },
+        new PhoneInput { Phone = phone2 }
+    });
+    if (resp.Summary.Total != 2) throw new Exception($"expected summary.total=2, got {resp.Summary.Total}");
+});
+
+// ── Cleanup & Results ──────────────────────────────────────────────────────────
+client.Dispose();
+if (File.Exists(pngPath)) File.Delete(pngPath);
+
+Console.WriteLine("\n==============================================");
+Console.WriteLine($"  RESULTS: {passed} passed, {failed} failed");
+Console.WriteLine("==============================================");
+
+var summary = JsonSerializer.Serialize(new { sdk = "dotnet", passed, failed, total = passed + failed });
+Console.WriteLine($"\nSUMMARY_JSON: {summary}");
+
+Environment.Exit(failed > 0 ? 1 : 0);
diff --git a/src/CCAI.NET/Brands/BrandModels.cs b/src/CCAI.NET/Brands/BrandModels.cs
new file mode 100644
index 0000000..22257b2
--- /dev/null
+++ b/src/CCAI.NET/Brands/BrandModels.cs
@@ -0,0 +1,138 @@
+// Copyright (c) 2025 CloudContactAI LLC
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using System.Text.Json.Serialization;
+
+namespace CCAI.NET.Brands;
+
+public class BrandRequest
+{
+    [JsonPropertyName("legalCompanyName")]
+    public string? LegalCompanyName { get; set; }
+    
+    [JsonPropertyName("dba")]
+    public string? Dba { get; set; }
+    
+    [JsonPropertyName("entityType")]
+    public string? EntityType { get; set; }
+    
+    [JsonPropertyName("taxId")]
+    public string? TaxId { get; set; }
+    
+    [JsonPropertyName("taxIdCountry")]
+    public string? TaxIdCountry { get; set; }
+    
+    [JsonPropertyName("country")]
+    public string? Country { get; set; }
+    
+    [JsonPropertyName("verticalType")]
+    public string? VerticalType { get; set; }
+    
+    [JsonPropertyName("websiteUrl")]
+    public string? WebsiteUrl { get; set; }
+    
+    [JsonPropertyName("stockSymbol")]
+    public string? StockSymbol { get; set; }
+    
+    [JsonPropertyName("stockExchange")]
+    public string? StockExchange { get; set; }
+    
+    [JsonPropertyName("street")]
+    public string? Street { get; set; }
+    
+    [JsonPropertyName("city")]
+    public string? City { get; set; }
+    
+    [JsonPropertyName("state")]
+    public string? State { get; set; }
+    
+    [JsonPropertyName("postalCode")]
+    public string? PostalCode { get; set; }
+    
+    [JsonPropertyName("contactFirstName")]
+    public string? ContactFirstName { get; set; }
+    
+    [JsonPropertyName("contactLastName")]
+    public string? ContactLastName { get; set; }
+    
+    [JsonPropertyName("contactEmail")]
+    public string? ContactEmail { get; set; }
+    
+    [JsonPropertyName("contactPhone")]
+    public string? ContactPhone { get; set; }
+    
+    [JsonPropertyName("websiteMatch")]
+    public bool WebsiteMatch { get; set; } = false;
+}
+
+public class BrandResponse
+{
+    [JsonPropertyName("id")]
+    public long Id { get; set; }
+    
+    [JsonPropertyName("accountId")]
+    public long AccountId { get; set; }
+    
+    [JsonPropertyName("legalCompanyName")]
+    public string LegalCompanyName { get; set; } = "";
+    
+    [JsonPropertyName("dba")]
+    public string? Dba { get; set; }
+    
+    [JsonPropertyName("entityType")]
+    public string EntityType { get; set; } = "";
+    
+    [JsonPropertyName("taxId")]
+    public string TaxId { get; set; } = "";
+    
+    [JsonPropertyName("taxIdCountry")]
+    public string TaxIdCountry { get; set; } = "";
+    
+    [JsonPropertyName("country")]
+    public string Country { get; set; } = "";
+    
+    [JsonPropertyName("verticalType")]
+    public string VerticalType { get; set; } = "";
+    
+    [JsonPropertyName("websiteUrl")]
+    public string WebsiteUrl { get; set; } = "";
+    
+    [JsonPropertyName("stockSymbol")]
+    public string? StockSymbol { get; set; }
+    
+    [JsonPropertyName("stockExchange")]
+    public string? StockExchange { get; set; }
+    
+    [JsonPropertyName("street")]
+    public string Street { get; set; } = "";
+    
+    [JsonPropertyName("city")]
+    public string City { get; set; } = "";
+    
+    [JsonPropertyName("state")]
+    public string State { get; set; } = "";
+    
+    [JsonPropertyName("postalCode")]
+    public string PostalCode { get; set; } = "";
+    
+    [JsonPropertyName("contactFirstName")]
+    public string ContactFirstName { get; set; } = "";
+    
+    [JsonPropertyName("contactLastName")]
+    public string ContactLastName { get; set; } = "";
+    
+    [JsonPropertyName("contactEmail")]
+    public string ContactEmail { get; set; } = "";
+    
+    [JsonPropertyName("contactPhone")]
+    public string ContactPhone { get; set; } = "";
+    
+    [JsonPropertyName("websiteMatchScore")]
+    public int? WebsiteMatchScore { get; set; }
+    
+    [JsonPropertyName("createdAt")]
+    public string CreatedAt { get; set; } = "";
+    
+    [JsonPropertyName("updatedAt")]
+    public string UpdatedAt { get; set; } = "";
+}
diff --git a/src/CCAI.NET/Brands/BrandService.cs b/src/CCAI.NET/Brands/BrandService.cs
new file mode 100644
index 0000000..b0f1de4
--- /dev/null
+++ b/src/CCAI.NET/Brands/BrandService.cs
@@ -0,0 +1,119 @@
+// Copyright (c) 2025 CloudContactAI LLC
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using System.Text.RegularExpressions;
+
+namespace CCAI.NET.Brands;
+
+/// <summary>
+/// Brand service for managing brand registrations
+/// </summary>
+public class BrandService
+{
+    private readonly CCAIClient _client;
+
+    private static readonly HashSet<string> EntityTypes = new()
+    {
+        "PRIVATE_PROFIT", "PUBLIC_PROFIT", "NON_PROFIT", "GOVERNMENT", "SOLE_PROPRIETOR"
+    };
+
+    private static readonly HashSet<string> VerticalTypes = new()
+    {
+        "AUTOMOTIVE", "AGRICULTURE", "BANKING", "COMMUNICATION", "CONSTRUCTION", "EDUCATION",
+        "ENERGY", "ENTERTAINMENT", "GOVERNMENT", "HEALTHCARE", "HOSPITALITY", "INSURANCE",
+        "LEGAL", "MANUFACTURING", "NON_PROFIT", "PROFESSIONAL", "REAL_ESTATE", "RETAIL",
+        "TECHNOLOGY", "TRANSPORTATION"
+    };
+
+    private static readonly HashSet<string> TaxIdCountries = new() { "US", "CA", "GB", "AU" };
+    private static readonly HashSet<string> StockExchanges = new() { "NASDAQ", "NYSE", "AMEX", "TSX", "LON", "JPX", "HKEX", "OTHER" };
+
+    public BrandService(CCAIClient client)
+    {
+        _client = client;
+    }
+
+    public async Task<BrandResponse> CreateAsync(BrandRequest data, CancellationToken cancellationToken = default)
+    {
+        Validate(data, isCreate: true);
+        return await _client.CustomRequestAsync<BrandResponse>(HttpMethod.Post, "/v1/brands", data, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public BrandResponse Create(BrandRequest data) => CreateAsync(data).GetAwaiter().GetResult();
+
+    public async Task<BrandResponse> GetAsync(long id, CancellationToken cancellationToken = default)
+    {
+        return await _client.CustomRequestAsync<BrandResponse>(HttpMethod.Get, $"/v1/brands/{id}", null, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public BrandResponse Get(long id) => GetAsync(id).GetAwaiter().GetResult();
+
+    public async Task<BrandResponse[]> ListAsync(CancellationToken cancellationToken = default)
+    {
+        return await _client.CustomRequestAsync<BrandResponse[]>(HttpMethod.Get, "/v1/brands", null, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public BrandResponse[] List() => ListAsync().GetAwaiter().GetResult();
+
+    public async Task<BrandResponse> UpdateAsync(long id, BrandRequest data, CancellationToken cancellationToken = default)
+    {
+        Validate(data, isCreate: false);
+        return await _client.CustomRequestAsync<BrandResponse>(HttpMethod.Patch, $"/v1/brands/{id}", data, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public BrandResponse Update(long id, BrandRequest data) => UpdateAsync(id, data).GetAwaiter().GetResult();
+
+    public async Task DeleteAsync(long id, CancellationToken cancellationToken = default)
+    {
+        await _client.CustomRequestWithoutResponseAsync(HttpMethod.Delete, $"/v1/brands/{id}", null, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public void Delete(long id) => DeleteAsync(id).GetAwaiter().GetResult();
+
+    private static void Validate(BrandRequest data, bool isCreate)
+    {
+        var errors = new List<string>();
+
+        if (isCreate)
+        {
+            if (string.IsNullOrWhiteSpace(data.LegalCompanyName)) errors.Add("legalCompanyName is required");
+            if (string.IsNullOrWhiteSpace(data.EntityType)) errors.Add("entityType is required");
+            if (string.IsNullOrWhiteSpace(data.TaxId)) errors.Add("taxId is required");
+            if (string.IsNullOrWhiteSpace(data.TaxIdCountry)) errors.Add("taxIdCountry is required");
+            if (string.IsNullOrWhiteSpace(data.Country)) errors.Add("country is required");
+            if (string.IsNullOrWhiteSpace(data.VerticalType)) errors.Add("verticalType is required");
+            if (string.IsNullOrWhiteSpace(data.WebsiteUrl)) errors.Add("websiteUrl is required");
+            if (string.IsNullOrWhiteSpace(data.Street)) errors.Add("street is required");
+            if (string.IsNullOrWhiteSpace(data.City)) errors.Add("city is required");
+            if (string.IsNullOrWhiteSpace(data.State)) errors.Add("state is required");
+            if (string.IsNullOrWhiteSpace(data.PostalCode)) errors.Add("postalCode is required");
+            if (string.IsNullOrWhiteSpace(data.ContactFirstName)) errors.Add("contactFirstName is required");
+            if (string.IsNullOrWhiteSpace(data.ContactLastName)) errors.Add("contactLastName is required");
+            if (string.IsNullOrWhiteSpace(data.ContactEmail)) errors.Add("contactEmail is required");
+            if (string.IsNullOrWhiteSpace(data.ContactPhone)) errors.Add("contactPhone is required");
+        }
+
+        if (data.EntityType != null && !EntityTypes.Contains(data.EntityType)) errors.Add("Invalid entity type");
+        if (data.VerticalType != null && !VerticalTypes.Contains(data.VerticalType)) errors.Add("Invalid vertical type");
+        if (data.TaxIdCountry != null && !TaxIdCountries.Contains(data.TaxIdCountry)) errors.Add("Invalid tax ID country");
+        if (data.StockExchange != null && !StockExchanges.Contains(data.StockExchange)) errors.Add("Invalid stock exchange");
+
+        if (data.WebsiteUrl != null && !data.WebsiteUrl.StartsWith("http://") && !data.WebsiteUrl.StartsWith("https://"))
+            errors.Add("Website URL must start with http:// or https://");
+
+        if (data.ContactEmail != null && !Regex.IsMatch(data.ContactEmail, @"^[^@\s]+@[^@\s]+\.[^@\s]+$"))
+            errors.Add("Invalid email format");
+
+        if (data.TaxId != null && data.TaxIdCountry is "US" or "CA" && !Regex.IsMatch(data.TaxId, @"^\d{9}$"))
+            errors.Add($"Tax ID must be exactly 9 digits for {data.TaxIdCountry}");
+
+        if (data.EntityType == "PUBLIC_PROFIT")
+        {
+            if (string.IsNullOrWhiteSpace(data.StockSymbol)) errors.Add("Stock symbol is required for PUBLIC_PROFIT entities");
+            if (string.IsNullOrWhiteSpace(data.StockExchange)) errors.Add("Stock exchange is required for PUBLIC_PROFIT entities");
+        }
+
+        if (errors.Count > 0)
+            throw new ArgumentException($"Validation failed: {string.Join(", ", errors)}");
+    }
+}
diff --git a/src/CCAI.NET/CCAI.NET.csproj b/src/CCAI.NET/CCAI.NET.csproj
index 479c99f..1dc26a5 100644
--- a/src/CCAI.NET/CCAI.NET.csproj
+++ b/src/CCAI.NET/CCAI.NET.csproj
@@ -6,7 +6,7 @@
     <Nullable>enable</Nullable>
     <LangVersion>latest</LangVersion>
     <PackageId>CloudContactAI.CCAI.NET</PackageId>
-    <Version>1.4.5</Version>
+    <Version>1.5.0</Version>
     <Authors>CloudContactAI LLC</Authors>
     <Company>CloudContactAI LLC</Company>
     <Description>C# client for CloudContactAI API with SMS, MMS, Email, and Webhook support. Enhanced webhook support with new CloudContact event format, contact.unsubscribed events, environment variable configuration, and comprehensive examples.</Description>
@@ -15,7 +15,7 @@
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <RepositoryUrl>https://github.com/CloudContactAI/CCAI.NET</RepositoryUrl>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-    <PackageReleaseNotes>$([System.IO.File]::ReadAllText("$(MSBuildProjectDirectory)/../../RELEASE-NOTES-v1.4.5.md"))</PackageReleaseNotes>
+    <PackageReleaseNotes>$([System.IO.File]::ReadAllText("$(MSBuildProjectDirectory)/../../RELEASE-NOTES-v1.5.0.md"))</PackageReleaseNotes>
     <PackageProjectUrl>https://github.com/CloudContactAI/CCAI.NET</PackageProjectUrl>
     <RepositoryType>git</RepositoryType>
     <PackageReadmeFile>README.md</PackageReadmeFile>
diff --git a/src/CCAI.NET/CCAIClient.cs b/src/CCAI.NET/CCAIClient.cs
index 5390a89..aee1400 100644
--- a/src/CCAI.NET/CCAIClient.cs
+++ b/src/CCAI.NET/CCAIClient.cs
@@ -6,7 +6,10 @@
 using System.Text;
 using System.Text.Json;
 using System.Text.Json.Serialization;
+using CCAI.NET.Brands;
+using CCAI.NET.Campaigns;
 using CCAI.NET.Contact;
+using CCAI.NET.ContactValidator;
 using CCAI.NET.Email;
 using CCAI.NET.SMS;
 using CCAI.NET.Webhook;
@@ -48,6 +51,21 @@ public interface ICCAIClient : IDisposable
     /// </summary>
     IContactService Contact { get; }
 
+    /// <summary>
+    /// Brand service for managing brand registrations
+    /// </summary>
+    BrandService Brands { get; }
+
+    /// <summary>
+    /// Campaign service for managing 10DLC campaign registrations
+    /// </summary>
+    CampaignService Campaigns { get; }
+
+    /// <summary>
+    /// Contact validator service for validating email and phone contacts
+    /// </summary>
+    IContactValidatorService ContactValidator { get; }
+
     /// <summary>
     /// Get the client ID
     /// </summary>
@@ -78,6 +96,11 @@ public interface ICCAIClient : IDisposable
     /// </summary>
     string GetFilesBaseUrl();
 
+    /// <summary>
+    /// Get the compliance base URL
+    /// </summary>
+    string GetComplianceBaseUrl();
+
     /// <summary>
     /// Make an authenticated API request to the CCAI API
     /// </summary>
@@ -99,6 +122,17 @@ Task<TResponse> CustomRequestAsync<TResponse>(
         CancellationToken cancellationToken = default,
         Dictionary<string, string>? headers = null);
 
+    /// <summary>
+    /// Make an authenticated API request to a custom API endpoint without expecting a JSON response
+    /// </summary>
+    Task CustomRequestWithoutResponseAsync(
+        HttpMethod method,
+        string endpoint,
+        object? data = null,
+        string? baseUrl = null,
+        CancellationToken cancellationToken = default,
+        Dictionary<string, string>? headers = null);
+
     /// <summary>
     /// Make an authenticated API request to the CCAI API without expecting a JSON response
     /// </summary>
@@ -144,6 +178,11 @@ public record CCAIConfig
     /// Base URL for the Files API
     /// </summary>
     public string FilesBaseUrl { get; init; } = Environment.GetEnvironmentVariable("CCAI_FILES_BASE_URL") ?? "https://files.cloudcontactai.com";
+
+    /// <summary>
+    /// Base URL for the Compliance API
+    /// </summary>
+    public string ComplianceBaseUrl { get; init; } = Environment.GetEnvironmentVariable("CCAI_COMPLIANCE_BASE_URL") ?? "https://compliance.cloudcontactai.com/api";
     
     /// <summary>
     /// Whether to use test environment URLs
@@ -189,6 +228,16 @@ public string GetFilesBaseUrl()
             ? Environment.GetEnvironmentVariable("CCAI_TEST_FILES_BASE_URL") ?? "https://files-test-cloudcontactai.allcode.com"
             : FilesBaseUrl;
     }
+
+    /// <summary>
+    /// Get the appropriate compliance base URL based on environment
+    /// </summary>
+    public string GetComplianceBaseUrl()
+    {
+        return UseTestEnvironment
+            ? Environment.GetEnvironmentVariable("CCAI_TEST_COMPLIANCE_BASE_URL") ?? "https://compliance-test-cloudcontactai.allcode.com/api"
+            : ComplianceBaseUrl;
+    }
 }
 
 /// <summary>
@@ -231,6 +280,21 @@ public class CCAIClient : ICCAIClient
     /// </summary>
     public IContactService Contact { get; }
 
+    /// <summary>
+    /// Brand service for managing brand registrations
+    /// </summary>
+    public BrandService Brands { get; }
+
+    /// <summary>
+    /// Campaign service for managing 10DLC campaign registrations
+    /// </summary>
+    public CampaignService Campaigns { get; }
+
+    /// <summary>
+    /// Contact validator service for validating email and phone contacts
+    /// </summary>
+    public IContactValidatorService ContactValidator { get; }
+
     /// <summary>
     /// Create a new CCAI client instance
     /// </summary>
@@ -278,31 +342,39 @@ public CCAIClient(CCAIConfig config, HttpClient? httpClient = null)
         Webhook = new WebhookService(this);
         Phone = new PhoneService(this);
         Contact = new ContactService(this);
+        Brands = new BrandService(this);
+        Campaigns = new CampaignService(this);
+        ContactValidator = new ContactValidatorService(this);
     }
 
     /// <summary>
     /// Get the client ID
     /// </summary>
+    /// <returns>Client ID</returns>
     public string GetClientId() => _config.ClientId;
 
     /// <summary>
     /// Get the API key
     /// </summary>
+    /// <returns>API key</returns>
     public string GetApiKey() => _config.ApiKey;
 
     /// <summary>
     /// Get the base URL
     /// </summary>
+    /// <returns>Base URL</returns>
     public string GetBaseUrl() => _config.GetBaseUrl();
-
+    
     /// <summary>
     /// Get the email base URL
     /// </summary>
+    /// <returns>Email base URL</returns>
     public string GetEmailBaseUrl() => _config.GetEmailBaseUrl();
-
+    
     /// <summary>
     /// Get the auth base URL
     /// </summary>
+    /// <returns>Auth base URL</returns>
     public string GetAuthBaseUrl() => _config.GetAuthBaseUrl();
 
     /// <summary>
@@ -310,9 +382,22 @@ public CCAIClient(CCAIConfig config, HttpClient? httpClient = null)
     /// </summary>
     public string GetFilesBaseUrl() => _config.GetFilesBaseUrl();
 
+    /// <summary>
+    /// Get the compliance base URL
+    /// </summary>
+    public string GetComplianceBaseUrl() => _config.GetComplianceBaseUrl();
+
     /// <summary>
     /// Make an authenticated API request to the CCAI API
     /// </summary>
+    /// <param name="method">HTTP method</param>
+    /// <param name="endpoint">API endpoint</param>
+    /// <param name="data">Request data</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <param name="headers">Additional headers</param>
+    /// <typeparam name="TResponse">Response type</typeparam>
+    /// <returns>API response</returns>
+    /// <exception cref="HttpRequestException">If the API returns an error</exception>
     public async Task<TResponse> RequestAsync<TResponse>(
         HttpMethod method,
         string endpoint,
@@ -326,6 +411,15 @@ public async Task<TResponse> RequestAsync<TResponse>(
     /// <summary>
     /// Make an authenticated API request to a custom API endpoint
     /// </summary>
+    /// <param name="method">HTTP method</param>
+    /// <param name="endpoint">API endpoint</param>
+    /// <param name="data">Request data</param>
+    /// <param name="baseUrl">Custom base URL for the API</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <param name="headers">Additional headers</param>
+    /// <typeparam name="TResponse">Response type</typeparam>
+    /// <returns>API response</returns>
+    /// <exception cref="HttpRequestException">If the API returns an error</exception>
     public async Task<TResponse> CustomRequestAsync<TResponse>(
         HttpMethod method,
         string endpoint,
@@ -335,15 +429,15 @@ public async Task<TResponse> CustomRequestAsync<TResponse>(
         Dictionary<string, string>? headers = null)
     {
         var url = $"{baseUrl ?? _config.GetBaseUrl()}{endpoint}";
-
+        
         using var request = new HttpRequestMessage(method, url);
-
+        
         if (data != null)
         {
             var json = JsonSerializer.Serialize(data, _jsonOptions);
             request.Content = new StringContent(json, Encoding.UTF8, "application/json");
         }
-
+        
         // Add additional headers if provided
         if (headers != null)
         {
@@ -352,20 +446,20 @@ public async Task<TResponse> CustomRequestAsync<TResponse>(
                 request.Headers.Add(key, value);
             }
         }
-
+        
         using var response = await _httpClient.SendAsync(request, cancellationToken);
-
+        
         // Throw an exception for HTTP errors
         response.EnsureSuccessStatusCode();
-
+        
         // Parse the response as JSON
         var result = await response.Content.ReadFromJsonAsync<TResponse>(_jsonOptions, cancellationToken);
-
+        
         if (result == null)
         {
             throw new InvalidOperationException("Failed to deserialize response");
         }
-
+        
         return result;
     }
 
@@ -405,16 +499,37 @@ public async Task RequestWithoutResponseAsync(
         CancellationToken cancellationToken = default,
         Dictionary<string, string>? headers = null)
     {
-        var url = $"{_config.GetBaseUrl()}{endpoint}";
-        
+        await CustomRequestWithoutResponseAsync(method, endpoint, data, _config.GetBaseUrl(), cancellationToken, headers);
+    }
+
+    /// <summary>
+    /// Make an authenticated API request to a custom API endpoint without expecting a JSON response
+    /// </summary>
+    /// <param name="method">HTTP method</param>
+    /// <param name="endpoint">API endpoint</param>
+    /// <param name="data">Request data</param>
+    /// <param name="baseUrl">Custom base URL for the API</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <param name="headers">Additional headers</param>
+    /// <exception cref="HttpRequestException">If the API returns an error</exception>
+    public async Task CustomRequestWithoutResponseAsync(
+        HttpMethod method,
+        string endpoint,
+        object? data = null,
+        string? baseUrl = null,
+        CancellationToken cancellationToken = default,
+        Dictionary<string, string>? headers = null)
+    {
+        var url = $"{baseUrl ?? _config.GetBaseUrl()}{endpoint}";
+
         using var request = new HttpRequestMessage(method, url);
-        
+
         if (data != null)
         {
             var json = JsonSerializer.Serialize(data, _jsonOptions);
             request.Content = new StringContent(json, Encoding.UTF8, "application/json");
         }
-        
+
         if (headers != null)
         {
             foreach (var (key, value) in headers)
@@ -422,7 +537,7 @@ public async Task RequestWithoutResponseAsync(
                 request.Headers.Add(key, value);
             }
         }
-        
+
         using var response = await _httpClient.SendAsync(request, cancellationToken);
         response.EnsureSuccessStatusCode();
     }
diff --git a/src/CCAI.NET/Campaigns/CampaignModels.cs b/src/CCAI.NET/Campaigns/CampaignModels.cs
new file mode 100644
index 0000000..e22613d
--- /dev/null
+++ b/src/CCAI.NET/Campaigns/CampaignModels.cs
@@ -0,0 +1,141 @@
+// Copyright (c) 2025 CloudContactAI LLC
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using System.Text.Json.Serialization;
+
+namespace CCAI.NET.Campaigns;
+
+public class CampaignRequest
+{
+    [JsonPropertyName("brandId")]
+    public long? BrandId { get; set; }
+    
+    [JsonPropertyName("useCase")]
+    public string? UseCase { get; set; }
+    
+    [JsonPropertyName("subUseCases")]
+    public List<string>? SubUseCases { get; set; }
+    
+    [JsonPropertyName("description")]
+    public string? Description { get; set; }
+    
+    [JsonPropertyName("messageFlow")]
+    public string? MessageFlow { get; set; }
+    
+    [JsonPropertyName("termsLink")]
+    public string? TermsLink { get; set; }
+    
+    [JsonPropertyName("privacyLink")]
+    public string? PrivacyLink { get; set; }
+    
+    [JsonPropertyName("hasEmbeddedLinks")]
+    public bool? HasEmbeddedLinks { get; set; }
+    
+    [JsonPropertyName("hasEmbeddedPhone")]
+    public bool? HasEmbeddedPhone { get; set; }
+    
+    [JsonPropertyName("isAgeGated")]
+    public bool? IsAgeGated { get; set; }
+    
+    [JsonPropertyName("isDirectLending")]
+    public bool? IsDirectLending { get; set; }
+    
+    [JsonPropertyName("optInKeywords")]
+    public List<string>? OptInKeywords { get; set; }
+    
+    [JsonPropertyName("optInMessage")]
+    public string? OptInMessage { get; set; }
+    
+    [JsonPropertyName("optInProofUrl")]
+    public string? OptInProofUrl { get; set; }
+    
+    [JsonPropertyName("helpKeywords")]
+    public List<string>? HelpKeywords { get; set; }
+    
+    [JsonPropertyName("helpMessage")]
+    public string? HelpMessage { get; set; }
+    
+    [JsonPropertyName("optOutKeywords")]
+    public List<string>? OptOutKeywords { get; set; }
+    
+    [JsonPropertyName("optOutMessage")]
+    public string? OptOutMessage { get; set; }
+    
+    [JsonPropertyName("sampleMessages")]
+    public List<string>? SampleMessages { get; set; }
+}
+
+public class CampaignResponse
+{
+    [JsonPropertyName("id")]
+    public long Id { get; set; }
+    
+    [JsonPropertyName("accountId")]
+    public long AccountId { get; set; }
+    
+    [JsonPropertyName("brandId")]
+    public long BrandId { get; set; }
+    
+    [JsonPropertyName("useCase")]
+    public string UseCase { get; set; } = "";
+    
+    [JsonPropertyName("subUseCases")]
+    public List<string> SubUseCases { get; set; } = new();
+    
+    [JsonPropertyName("description")]
+    public string Description { get; set; } = "";
+    
+    [JsonPropertyName("messageFlow")]
+    public string MessageFlow { get; set; } = "";
+    
+    [JsonPropertyName("termsLink")]
+    public string? TermsLink { get; set; }
+    
+    [JsonPropertyName("privacyLink")]
+    public string? PrivacyLink { get; set; }
+    
+    [JsonPropertyName("hasEmbeddedLinks")]
+    public bool HasEmbeddedLinks { get; set; }
+    
+    [JsonPropertyName("hasEmbeddedPhone")]
+    public bool HasEmbeddedPhone { get; set; }
+    
+    [JsonPropertyName("isAgeGated")]
+    public bool IsAgeGated { get; set; }
+    
+    [JsonPropertyName("isDirectLending")]
+    public bool IsDirectLending { get; set; }
+    
+    [JsonPropertyName("optInKeywords")]
+    public List<string> OptInKeywords { get; set; } = new();
+    
+    [JsonPropertyName("optInMessage")]
+    public string OptInMessage { get; set; } = "";
+    
+    [JsonPropertyName("optInProofUrl")]
+    public string OptInProofUrl { get; set; } = "";
+    
+    [JsonPropertyName("helpKeywords")]
+    public List<string> HelpKeywords { get; set; } = new();
+    
+    [JsonPropertyName("helpMessage")]
+    public string HelpMessage { get; set; } = "";
+    
+    [JsonPropertyName("optOutKeywords")]
+    public List<string> OptOutKeywords { get; set; } = new();
+    
+    [JsonPropertyName("optOutMessage")]
+    public string OptOutMessage { get; set; } = "";
+    
+    [JsonPropertyName("sampleMessages")]
+    public List<string> SampleMessages { get; set; } = new();
+    
+    [JsonPropertyName("monthlyFee")]
+    public decimal MonthlyFee { get; set; }
+    
+    [JsonPropertyName("createdAt")]
+    public string CreatedAt { get; set; } = "";
+    
+    [JsonPropertyName("updatedAt")]
+    public string UpdatedAt { get; set; } = "";
+}
diff --git a/src/CCAI.NET/Campaigns/CampaignService.cs b/src/CCAI.NET/Campaigns/CampaignService.cs
new file mode 100644
index 0000000..a6b6a2a
--- /dev/null
+++ b/src/CCAI.NET/Campaigns/CampaignService.cs
@@ -0,0 +1,163 @@
+// Copyright (c) 2025 CloudContactAI LLC
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+namespace CCAI.NET.Campaigns;
+
+/// <summary>
+/// Campaign service for managing 10DLC campaign registrations
+/// </summary>
+public class CampaignService
+{
+    private readonly CCAIClient _client;
+
+    private static readonly HashSet<string> UseCases = new()
+    {
+        "TWO_FACTOR_AUTHENTICATION", "ACCOUNT_NOTIFICATION", "CUSTOMER_CARE", "DELIVERY_NOTIFICATION",
+        "FRAUD_ALERT", "HIGHER_EDUCATION", "LOW_VOLUME_MIXED", "MARKETING", "MIXED",
+        "POLLING_VOTING", "PUBLIC_SERVICE_ANNOUNCEMENT", "SECURITY_ALERT"
+    };
+
+    private static readonly HashSet<string> SubUseCases = new()
+    {
+        "TWO_FACTOR_AUTHENTICATION", "ACCOUNT_NOTIFICATION", "CUSTOMER_CARE", "DELIVERY_NOTIFICATION",
+        "FRAUD_ALERT", "MARKETING", "POLLING_VOTING"
+    };
+
+    private static readonly HashSet<string> MixedUseCases = new() { "MIXED", "LOW_VOLUME_MIXED" };
+
+    public CampaignService(CCAIClient client)
+    {
+        _client = client;
+    }
+
+    public async Task<CampaignResponse> CreateAsync(CampaignRequest data, CancellationToken cancellationToken = default)
+    {
+        Validate(data, isCreate: true);
+        return await _client.CustomRequestAsync<CampaignResponse>(HttpMethod.Post, "/v1/campaigns", data, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public CampaignResponse Create(CampaignRequest data) => CreateAsync(data).GetAwaiter().GetResult();
+
+    public async Task<CampaignResponse> GetAsync(long id, CancellationToken cancellationToken = default)
+    {
+        return await _client.CustomRequestAsync<CampaignResponse>(HttpMethod.Get, $"/v1/campaigns/{id}", null, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public CampaignResponse Get(long id) => GetAsync(id).GetAwaiter().GetResult();
+
+    public async Task<CampaignResponse[]> ListAsync(CancellationToken cancellationToken = default)
+    {
+        return await _client.CustomRequestAsync<CampaignResponse[]>(HttpMethod.Get, "/v1/campaigns", null, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public CampaignResponse[] List() => ListAsync().GetAwaiter().GetResult();
+
+    public async Task<CampaignResponse> UpdateAsync(long id, CampaignRequest data, CancellationToken cancellationToken = default)
+    {
+        Validate(data, isCreate: false);
+        return await _client.CustomRequestAsync<CampaignResponse>(HttpMethod.Patch, $"/v1/campaigns/{id}", data, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public CampaignResponse Update(long id, CampaignRequest data) => UpdateAsync(id, data).GetAwaiter().GetResult();
+
+    public async Task DeleteAsync(long id, CancellationToken cancellationToken = default)
+    {
+        await _client.CustomRequestWithoutResponseAsync(HttpMethod.Delete, $"/v1/campaigns/{id}", null, _client.GetComplianceBaseUrl(), cancellationToken);
+    }
+
+    public void Delete(long id) => DeleteAsync(id).GetAwaiter().GetResult();
+
+    private static void Validate(CampaignRequest data, bool isCreate)
+    {
+        var errors = new List<string>();
+
+        if (isCreate)
+        {
+            if (data.BrandId == null) errors.Add("brandId is required");
+            if (string.IsNullOrWhiteSpace(data.UseCase)) errors.Add("useCase is required");
+            if (string.IsNullOrWhiteSpace(data.Description)) errors.Add("description is required");
+            if (string.IsNullOrWhiteSpace(data.MessageFlow)) errors.Add("messageFlow is required");
+            if (data.HasEmbeddedLinks == null) errors.Add("hasEmbeddedLinks is required");
+            if (data.HasEmbeddedPhone == null) errors.Add("hasEmbeddedPhone is required");
+            if (data.IsAgeGated == null) errors.Add("isAgeGated is required");
+            if (data.IsDirectLending == null) errors.Add("isDirectLending is required");
+            if (data.OptInKeywords == null || data.OptInKeywords.Count == 0) errors.Add("optInKeywords is required");
+            if (string.IsNullOrWhiteSpace(data.OptInMessage)) errors.Add("optInMessage is required");
+            if (string.IsNullOrWhiteSpace(data.OptInProofUrl)) errors.Add("optInProofUrl is required");
+            if (data.HelpKeywords == null || data.HelpKeywords.Count == 0) errors.Add("helpKeywords is required");
+            if (string.IsNullOrWhiteSpace(data.HelpMessage)) errors.Add("helpMessage is required");
+            if (data.OptOutKeywords == null || data.OptOutKeywords.Count == 0) errors.Add("optOutKeywords is required");
+            if (string.IsNullOrWhiteSpace(data.OptOutMessage)) errors.Add("optOutMessage is required");
+            if (data.SampleMessages == null || data.SampleMessages.Count == 0) errors.Add("sampleMessages is required");
+        }
+
+        if (data.UseCase != null && !UseCases.Contains(data.UseCase))
+            errors.Add("Invalid use case");
+
+        // MIXED/LOW_VOLUME_MIXED sub-use case validation
+        if (data.UseCase != null && MixedUseCases.Contains(data.UseCase))
+        {
+            if (data.SubUseCases == null || data.SubUseCases.Count < 2 || data.SubUseCases.Count > 3)
+                errors.Add("MIXED/LOW_VOLUME_MIXED requires 2-3 sub use cases");
+            else
+                foreach (var suc in data.SubUseCases)
+                    if (!SubUseCases.Contains(suc)) errors.Add($"Invalid sub use case: {suc}");
+        }
+        else if (data.UseCase != null && data.SubUseCases is { Count: > 0 })
+        {
+            errors.Add("subUseCases should be empty for non-MIXED use cases");
+        }
+
+        // sampleMessages count and content validation
+        if (data.SampleMessages != null)
+        {
+            if (data.SampleMessages.Count < 2 || data.SampleMessages.Count > 5)
+            {
+                errors.Add("sampleMessages must contain 2-5 items");
+            }
+            else
+            {
+                var optOutKws = data.OptOutKeywords ?? new List<string>();
+                var helpKws = data.HelpKeywords ?? new List<string>();
+
+                var hasOptOut = data.SampleMessages.Any(msg =>
+                    msg.Contains("Reply STOP") || optOutKws.Any(kw => msg.Contains($"Reply {kw}")));
+                if (!hasOptOut)
+                    errors.Add("At least one sample must contain 'Reply STOP' or 'Reply {optOutKeyword}'");
+
+                var hasHelp = data.SampleMessages.Any(msg =>
+                    msg.Contains("Reply HELP") || helpKws.Any(kw => msg.Contains($"Reply {kw}")));
+                if (!hasHelp)
+                    errors.Add("At least one sample must contain 'Reply HELP' or 'Reply {helpKeyword}'");
+            }
+        }
+
+        // optOutMessage must contain STOP or an opt-out keyword
+        if (data.OptOutMessage != null)
+        {
+            var optOutKws = data.OptOutKeywords ?? new List<string>();
+            if (!data.OptOutMessage.Contains("STOP") && !optOutKws.Any(kw => data.OptOutMessage.Contains(kw)))
+                errors.Add("optOutMessage must contain 'STOP' or at least one optOutKeyword");
+        }
+
+        // helpMessage must contain HELP or a help keyword
+        if (data.HelpMessage != null)
+        {
+            var helpKws = data.HelpKeywords ?? new List<string>();
+            if (!data.HelpMessage.Contains("HELP") && !helpKws.Any(kw => data.HelpMessage.Contains(kw)))
+                errors.Add("helpMessage must contain 'HELP' or at least one helpKeyword");
+        }
+
+        if (data.OptInProofUrl != null && !data.OptInProofUrl.StartsWith("http://") && !data.OptInProofUrl.StartsWith("https://"))
+            errors.Add("Opt-in proof URL must start with http:// or https://");
+
+        if (data.TermsLink != null && !data.TermsLink.StartsWith("http://") && !data.TermsLink.StartsWith("https://"))
+            errors.Add("Terms link must start with http:// or https://");
+
+        if (data.PrivacyLink != null && !data.PrivacyLink.StartsWith("http://") && !data.PrivacyLink.StartsWith("https://"))
+            errors.Add("Privacy link must start with http:// or https://");
+
+        if (errors.Count > 0)
+            throw new ArgumentException($"Validation failed: {string.Join(", ", errors)}");
+    }
+}
diff --git a/src/CCAI.NET/ContactValidator/ContactValidatorModels.cs b/src/CCAI.NET/ContactValidator/ContactValidatorModels.cs
new file mode 100644
index 0000000..6b0ac52
--- /dev/null
+++ b/src/CCAI.NET/ContactValidator/ContactValidatorModels.cs
@@ -0,0 +1,139 @@
+// Copyright (c) 2025 CloudContactAI LLC
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace CCAI.NET.ContactValidator;
+
+/// <summary>
+/// Validation result for a single email address
+/// </summary>
+public class EmailValidationResult
+{
+    /// <summary>
+    /// The validated email address
+    /// </summary>
+    [JsonPropertyName("contact")]
+    public string Contact { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Contact type — always "email"
+    /// </summary>
+    [JsonPropertyName("type")]
+    public string Type { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Validation status: "valid", "invalid", or "risky"
+    /// </summary>
+    [JsonPropertyName("status")]
+    public string Status { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Additional metadata (e.g. safe_to_send, ai_verdict)
+    /// </summary>
+    [JsonPropertyName("metadata")]
+    public Dictionary<string, JsonElement>? Metadata { get; set; }
+}
+
+/// <summary>
+/// Validation result for a single phone number
+/// </summary>
+public class PhoneValidationResult
+{
+    /// <summary>
+    /// The validated phone number
+    /// </summary>
+    [JsonPropertyName("contact")]
+    public string Contact { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Contact type — always "phone"
+    /// </summary>
+    [JsonPropertyName("type")]
+    public string Type { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Validation status: "valid", "invalid", or "landline"
+    /// </summary>
+    [JsonPropertyName("status")]
+    public string Status { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Additional metadata (e.g. country_code, national_number, carrier_type)
+    /// </summary>
+    [JsonPropertyName("metadata")]
+    public Dictionary<string, JsonElement>? Metadata { get; set; }
+}
+
+/// <summary>
+/// Aggregate counts for a bulk validation response
+/// </summary>
+public class ValidationSummary
+{
+    /// <summary>Total contacts validated</summary>
+    [JsonPropertyName("total")]
+    public int Total { get; set; }
+
+    /// <summary>Number of valid contacts</summary>
+    [JsonPropertyName("valid")]
+    public int Valid { get; set; }
+
+    /// <summary>Number of invalid contacts</summary>
+    [JsonPropertyName("invalid")]
+    public int Invalid { get; set; }
+
+    /// <summary>Number of risky contacts (emails only)</summary>
+    [JsonPropertyName("risky")]
+    public int Risky { get; set; }
+
+    /// <summary>Number of landline numbers (phones only)</summary>
+    [JsonPropertyName("landline")]
+    public int Landline { get; set; }
+}
+
+/// <summary>
+/// Response for a bulk email validation request
+/// </summary>
+public class BulkEmailValidationResult
+{
+    /// <summary>Individual validation results</summary>
+    [JsonPropertyName("results")]
+    public List<EmailValidationResult> Results { get; set; } = new();
+
+    /// <summary>Aggregate summary</summary>
+    [JsonPropertyName("summary")]
+    public ValidationSummary Summary { get; set; } = new();
+}
+
+/// <summary>
+/// Response for a bulk phone validation request
+/// </summary>
+public class BulkPhoneValidationResult
+{
+    /// <summary>Individual validation results</summary>
+    [JsonPropertyName("results")]
+    public List<PhoneValidationResult> Results { get; set; } = new();
+
+    /// <summary>Aggregate summary</summary>
+    [JsonPropertyName("summary")]
+    public ValidationSummary Summary { get; set; } = new();
+}
+
+/// <summary>
+/// Phone number input for bulk validation
+/// </summary>
+public class PhoneInput
+{
+    /// <summary>
+    /// Phone number in E.164 format (e.g. +15551234567)
+    /// </summary>
+    [JsonPropertyName("phone")]
+    public string Phone { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Optional ISO 3166-1 alpha-2 country code (e.g. "US")
+    /// </summary>
+    [JsonPropertyName("countryCode")]
+    public string? CountryCode { get; set; }
+}
diff --git a/src/CCAI.NET/ContactValidator/ContactValidatorService.cs b/src/CCAI.NET/ContactValidator/ContactValidatorService.cs
new file mode 100644
index 0000000..793c016
--- /dev/null
+++ b/src/CCAI.NET/ContactValidator/ContactValidatorService.cs
@@ -0,0 +1,104 @@
+// Copyright (c) 2025 CloudContactAI LLC
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+namespace CCAI.NET.ContactValidator;
+
+/// <summary>
+/// Interface for the contact validator service
+/// </summary>
+public interface IContactValidatorService
+{
+    /// <summary>Validate a single email address (async)</summary>
+    Task<EmailValidationResult> ValidateEmailAsync(string email, CancellationToken cancellationToken = default);
+
+    /// <summary>Validate multiple email addresses up to the configured bulk limit (async)</summary>
+    Task<BulkEmailValidationResult> ValidateEmailsAsync(IEnumerable<string> emails, CancellationToken cancellationToken = default);
+
+    /// <summary>Validate a single phone number in E.164 format (async)</summary>
+    Task<PhoneValidationResult> ValidatePhoneAsync(string phone, string? countryCode = null, CancellationToken cancellationToken = default);
+
+    /// <summary>Validate multiple phone numbers up to the configured bulk limit (async)</summary>
+    Task<BulkPhoneValidationResult> ValidatePhonesAsync(IEnumerable<PhoneInput> phones, CancellationToken cancellationToken = default);
+
+    /// <summary>Validate a single email address (synchronous)</summary>
+    EmailValidationResult ValidateEmail(string email);
+
+    /// <summary>Validate multiple email addresses up to the configured bulk limit (synchronous)</summary>
+    BulkEmailValidationResult ValidateEmails(IEnumerable<string> emails);
+
+    /// <summary>Validate a single phone number in E.164 format (synchronous)</summary>
+    PhoneValidationResult ValidatePhone(string phone, string? countryCode = null);
+
+    /// <summary>Validate multiple phone numbers up to the configured bulk limit (synchronous)</summary>
+    BulkPhoneValidationResult ValidatePhones(IEnumerable<PhoneInput> phones);
+}
+
+/// <summary>
+/// Service for validating email addresses and phone numbers through the CCAI API
+/// </summary>
+public class ContactValidatorService : IContactValidatorService
+{
+    private readonly ICCAIClient _client;
+
+    /// <summary>
+    /// Create a new ContactValidatorService instance
+    /// </summary>
+    /// <param name="client">The parent CCAI client</param>
+    public ContactValidatorService(ICCAIClient client)
+    {
+        _client = client;
+    }
+
+    /// <summary>
+    /// Validate a single email address
+    /// </summary>
+    /// <param name="email">Email address to validate</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Validation result with status and metadata</returns>
+    public Task<EmailValidationResult> ValidateEmailAsync(string email, CancellationToken cancellationToken = default) =>
+        _client.RequestAsync<EmailValidationResult>(HttpMethod.Post, "/v1/contact-validator/email", new { email }, cancellationToken);
+
+    /// <summary>
+    /// Validate multiple email addresses (up to the configured bulk limit)
+    /// </summary>
+    /// <param name="emails">List of email addresses to validate</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Bulk validation results with summary</returns>
+    public Task<BulkEmailValidationResult> ValidateEmailsAsync(IEnumerable<string> emails, CancellationToken cancellationToken = default) =>
+        _client.RequestAsync<BulkEmailValidationResult>(HttpMethod.Post, "/v1/contact-validator/emails", new { emails }, cancellationToken);
+
+    /// <summary>
+    /// Validate a single phone number
+    /// </summary>
+    /// <param name="phone">Phone number in E.164 format (e.g. +15551234567)</param>
+    /// <param name="countryCode">Optional ISO 3166-1 alpha-2 country code (e.g. "US")</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Validation result with status and metadata</returns>
+    public Task<PhoneValidationResult> ValidatePhoneAsync(string phone, string? countryCode = null, CancellationToken cancellationToken = default) =>
+        _client.RequestAsync<PhoneValidationResult>(HttpMethod.Post, "/v1/contact-validator/phone", new { phone, countryCode }, cancellationToken);
+
+    /// <summary>
+    /// Validate multiple phone numbers (up to the configured bulk limit)
+    /// </summary>
+    /// <param name="phones">List of phone inputs with optional country codes</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Bulk validation results with summary</returns>
+    public Task<BulkPhoneValidationResult> ValidatePhonesAsync(IEnumerable<PhoneInput> phones, CancellationToken cancellationToken = default) =>
+        _client.RequestAsync<BulkPhoneValidationResult>(HttpMethod.Post, "/v1/contact-validator/phones", new { phones }, cancellationToken);
+
+    /// <inheritdoc/>
+    public EmailValidationResult ValidateEmail(string email) =>
+        ValidateEmailAsync(email).GetAwaiter().GetResult();
+
+    /// <inheritdoc/>
+    public BulkEmailValidationResult ValidateEmails(IEnumerable<string> emails) =>
+        ValidateEmailsAsync(emails).GetAwaiter().GetResult();
+
+    /// <inheritdoc/>
+    public PhoneValidationResult ValidatePhone(string phone, string? countryCode = null) =>
+        ValidatePhoneAsync(phone, countryCode).GetAwaiter().GetResult();
+
+    /// <inheritdoc/>
+    public BulkPhoneValidationResult ValidatePhones(IEnumerable<PhoneInput> phones) =>
+        ValidatePhonesAsync(phones).GetAwaiter().GetResult();
+}