diff --git a/sdk/communication/Azure.Communication.Sms/src/OptOutsClient.cs b/sdk/communication/Azure.Communication.Sms/src/OptOutsClient.cs
index fefadc9600e0a..c62bb86500229 100644
--- a/sdk/communication/Azure.Communication.Sms/src/OptOutsClient.cs
+++ b/sdk/communication/Azure.Communication.Sms/src/OptOutsClient.cs
@@ -47,9 +47,9 @@ protected OptOutsClient()
         /// <exception cref="RequestFailedException">The server returned an error. See <see cref="Exception.Message"/> for details returned from the server.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="from"/> is null.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="to"/> is null.</exception>
-        public virtual async Task<Response<OptOutResponse>> CheckAsync(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
+        public virtual async Task<Response<IReadOnlyList<OptOutResponseItem>>> CheckAsync(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
         {
-            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(SmsClient)}.{nameof(OptOutsClient)}.{nameof(CheckAsync)}");
+            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(OptOutsClient)}.{nameof(Check)}");
             scope.Start();
             try
             {
@@ -58,7 +58,7 @@ public virtual async Task<Response<OptOutResponse>> CheckAsync(string from, IEnu
                 IEnumerable<OptOutRecipient> recipients = to.Select(x => new OptOutRecipient(Argument.CheckNotNullOrEmpty(x, nameof(to))));
 
                 Response<OptOutResponse> response = await OptOutsRestClient.CheckAsync(from, recipients, cancellationToken).ConfigureAwait(false);
-                return Response.FromValue(response.Value, response.GetRawResponse());
+                return Response.FromValue(response.Value.Value, response.GetRawResponse());
             }
             catch (Exception ex)
             {
@@ -76,9 +76,9 @@ public virtual async Task<Response<OptOutResponse>> CheckAsync(string from, IEnu
         /// <exception cref="RequestFailedException">The server returned an error. See <see cref="Exception.Message"/> for details returned from the server.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="from"/> is null.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="to"/> is null.</exception>
-        public virtual Response<OptOutResponse> Check(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
+        public virtual Response<IReadOnlyList<OptOutResponseItem>> Check(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
         {
-            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(SmsClient)}.{nameof(OptOutsClient)}.{nameof(Check)}");
+            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(OptOutsClient)}.{nameof(Check)}");
             scope.Start();
             try
             {
@@ -88,7 +88,7 @@ public virtual Response<OptOutResponse> Check(string from, IEnumerable<string> t
                 IEnumerable<OptOutRecipient> recipients = to.Select(x => new OptOutRecipient(Argument.CheckNotNullOrEmpty(x, nameof(to))));
 
                 Response<OptOutResponse> response = OptOutsRestClient.Check(from, recipients, cancellationToken);
-                return Response.FromValue(response.Value, response.GetRawResponse());
+                return Response.FromValue(response.Value.Value, response.GetRawResponse());
             }
             catch (Exception ex)
             {
@@ -106,9 +106,9 @@ public virtual Response<OptOutResponse> Check(string from, IEnumerable<string> t
         /// <exception cref="RequestFailedException">The server returned an error. See <see cref="Exception.Message"/> for details returned from the server.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="from"/> is null.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="to"/> is null.</exception>
-        public virtual async Task<Response<OptOutChangeResponse>> AddAsync(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
+        public virtual async Task<Response<IReadOnlyList<OptOutChangeResponseItem>>> AddAsync(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
         {
-            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(SmsClient)}.{nameof(OptOutsClient)}.{nameof(AddAsync)}");
+            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(OptOutsClient)}.{nameof(Add)}");
             scope.Start();
             try
             {
@@ -119,7 +119,7 @@ public virtual async Task<Response<OptOutChangeResponse>> AddAsync(string from,
                 Response<OptOutResponse> response = await OptOutsRestClient.AddAsync(from, recipients, cancellationToken).ConfigureAwait(false);
                 OptOutChangeResponse result = new OptOutChangeResponse(response.Value.Value.Select(r => new OptOutChangeResponseItem(r.To, r.HttpStatusCode, r.ErrorMessage)));
 
-                return Response.FromValue(result, response.GetRawResponse());
+                return Response.FromValue(result.Value, response.GetRawResponse());
             }
             catch (Exception ex)
             {
@@ -137,9 +137,9 @@ public virtual async Task<Response<OptOutChangeResponse>> AddAsync(string from,
         /// <exception cref="RequestFailedException">The server returned an error. See <see cref="Exception.Message"/> for details returned from the server.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="from"/> is null.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="to"/> is null.</exception>
-        public virtual Response<OptOutChangeResponse> Add(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
+        public virtual Response<IReadOnlyList<OptOutChangeResponseItem>> Add(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
         {
-            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(SmsClient)}.{nameof(OptOutsClient)}.{nameof(Add)}");
+            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(OptOutsClient)}.{nameof(Add)}");
             scope.Start();
             try
             {
@@ -150,7 +150,7 @@ public virtual Response<OptOutChangeResponse> Add(string from, IEnumerable<strin
                 Response<OptOutResponse> response = OptOutsRestClient.Add(from, recipients, cancellationToken);
                 OptOutChangeResponse result = new OptOutChangeResponse(response.Value.Value.Select(r => new OptOutChangeResponseItem(r.To, r.HttpStatusCode, r.ErrorMessage)));
 
-                return Response.FromValue(result, response.GetRawResponse());
+                return Response.FromValue(result.Value, response.GetRawResponse());
             }
             catch (Exception ex)
             {
@@ -168,9 +168,9 @@ public virtual Response<OptOutChangeResponse> Add(string from, IEnumerable<strin
         /// <exception cref="RequestFailedException">The server returned an error. See <see cref="Exception.Message"/> for details returned from the server.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="from"/> is null.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="to"/> is null.</exception>
-        public virtual async Task<Response<OptOutChangeResponse>> RemoveAsync(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
+        public virtual async Task<Response<IReadOnlyList<OptOutChangeResponseItem>>> RemoveAsync(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
         {
-            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(SmsClient)}.{nameof(OptOutsClient)}.{nameof(RemoveAsync)}");
+            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(OptOutsClient)}.{nameof(Remove)}");
             scope.Start();
             try
             {
@@ -181,7 +181,7 @@ public virtual async Task<Response<OptOutChangeResponse>> RemoveAsync(string fro
                 Response<OptOutResponse> response = await OptOutsRestClient.RemoveAsync(from, recipients, cancellationToken).ConfigureAwait(false);
                 OptOutChangeResponse result = new OptOutChangeResponse(response.Value.Value.Select(r => new OptOutChangeResponseItem(r.To, r.HttpStatusCode, r.ErrorMessage)));
 
-                return Response.FromValue(result, response.GetRawResponse());
+                return Response.FromValue(result.Value, response.GetRawResponse());
             }
             catch (Exception ex)
             {
@@ -199,9 +199,9 @@ public virtual async Task<Response<OptOutChangeResponse>> RemoveAsync(string fro
         /// <exception cref="RequestFailedException">The server returned an error. See <see cref="Exception.Message"/> for details returned from the server.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="from"/> is null.</exception>
         /// <exception cref="ArgumentNullException"><paramref name="to"/> is null.</exception>
-        public virtual Response<OptOutChangeResponse> Remove(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
+        public virtual Response<IReadOnlyList<OptOutChangeResponseItem>> Remove(string from, IEnumerable<string> to, CancellationToken cancellationToken = default)
         {
-            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(SmsClient)}.{nameof(OptOutsClient)}.{nameof(Remove)}");
+            using DiagnosticScope scope = _clientDiagnostics.CreateScope($"{nameof(OptOutsClient)}.{nameof(Remove)}");
             scope.Start();
             try
             {
@@ -212,7 +212,7 @@ public virtual Response<OptOutChangeResponse> Remove(string from, IEnumerable<st
                 Response<OptOutResponse> response = OptOutsRestClient.Remove(from, recipients, cancellationToken);
                 OptOutChangeResponse result = new OptOutChangeResponse(response.Value.Value.Select(r => new OptOutChangeResponseItem(r.To, r.HttpStatusCode, r.ErrorMessage)));
 
-                return Response.FromValue(result, response.GetRawResponse());
+                return Response.FromValue(result.Value, response.GetRawResponse());
             }
             catch (Exception ex)
             {
diff --git a/sdk/communication/Azure.Communication.Sms/tests/OptOutsClientTest.cs b/sdk/communication/Azure.Communication.Sms/tests/OptOutsClientTest.cs
index a3fdf06404ac1..509d00d6250d0 100644
--- a/sdk/communication/Azure.Communication.Sms/tests/OptOutsClientTest.cs
+++ b/sdk/communication/Azure.Communication.Sms/tests/OptOutsClientTest.cs
@@ -3,7 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Linq.Expressions;
 using System.Threading;
 using System.Threading.Tasks;
@@ -47,7 +46,7 @@ public void OptOutsClient_ThrowsWithNullEndpoint()
         public async Task CheckAsyncOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<string> expectedTo)
         {
             Mock<OptOutsClient> mockClient = new Mock<OptOutsClient>() { CallBase = true };
-            Response<OptOutResponse>? expectedResponse = default;
+            Response<IReadOnlyList<OptOutResponseItem>>? expectedResponse = default;
             CancellationToken cancellationToken = new CancellationTokenSource().Token;
             var callExpression = BuildExpression(x => x.CheckAsync(It.IsAny<string>(), It.IsAny<IEnumerable<string>>(), It.IsAny<CancellationToken>()));
 
@@ -58,10 +57,10 @@ public async Task CheckAsyncOverload_PassesToGeneratedOne(string expectedFrom, I
                     Assert.AreEqual(expectedFrom, from);
                     Assert.AreEqual(expectedTo, to);
                     Assert.AreEqual(cancellationToken, token);
-                    return expectedResponse = new Mock<Response<OptOutResponse>>().Object;
+                    return expectedResponse = new Mock<Response<IReadOnlyList<OptOutResponseItem>>>().Object;
                 });
 
-            Response<OptOutResponse> actualResponse = await mockClient.Object.CheckAsync(expectedFrom, expectedTo, cancellationToken);
+            Response<IReadOnlyList<OptOutResponseItem>> actualResponse = await mockClient.Object.CheckAsync(expectedFrom, expectedTo, cancellationToken);
 
             mockClient.Verify(callExpression, Times.Once());
             Assert.AreEqual(expectedResponse, actualResponse);
@@ -71,7 +70,7 @@ public async Task CheckAsyncOverload_PassesToGeneratedOne(string expectedFrom, I
         public void CheckOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<string> expectedTo)
         {
             Mock<OptOutsClient> mockClient = new Mock<OptOutsClient>() { CallBase = true };
-            Response<OptOutResponse>? expectedResponse = default;
+            Response<IReadOnlyList<OptOutResponseItem>>? expectedResponse = default;
             CancellationToken cancellationToken = new CancellationTokenSource().Token;
             var callExpression = BuildExpression(x => x.Check(It.IsAny<string>(), It.IsAny<IEnumerable<string>>(), It.IsAny<CancellationToken>()));
 
@@ -82,10 +81,10 @@ public void CheckOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<
                     Assert.AreEqual(expectedFrom, from);
                     Assert.AreEqual(expectedTo, to);
                     Assert.AreEqual(cancellationToken, token);
-                    return expectedResponse = new Mock<Response<OptOutResponse>>().Object;
+                    return expectedResponse = new Mock<Response<IReadOnlyList<OptOutResponseItem>>>().Object;
                 });
 
-            Response<OptOutResponse> actualResponse = mockClient.Object.Check(expectedFrom, expectedTo, cancellationToken);
+            Response<IReadOnlyList<OptOutResponseItem>> actualResponse = mockClient.Object.Check(expectedFrom, expectedTo, cancellationToken);
 
             mockClient.Verify(callExpression, Times.Once());
             Assert.AreEqual(expectedResponse, actualResponse);
@@ -95,7 +94,7 @@ public void CheckOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<
         public async Task AddAsyncOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<string> expectedTo)
         {
             Mock<OptOutsClient> mockClient = new Mock<OptOutsClient>() { CallBase = true };
-            Response<OptOutChangeResponse>? expectedResponse = default;
+            Response<IReadOnlyList<OptOutChangeResponseItem>>? expectedResponse = default;
             CancellationToken cancellationToken = new CancellationTokenSource().Token;
             var callExpression = BuildExpression(x => x.AddAsync(It.IsAny<string>(), It.IsAny<IEnumerable<string>>(), It.IsAny<CancellationToken>()));
 
@@ -106,10 +105,10 @@ public async Task AddAsyncOverload_PassesToGeneratedOne(string expectedFrom, IEn
                     Assert.AreEqual(expectedFrom, from);
                     Assert.AreEqual(expectedTo, to);
                     Assert.AreEqual(cancellationToken, token);
-                    return expectedResponse = new Mock<Response<OptOutChangeResponse>>().Object;
+                    return expectedResponse = new Mock<Response<IReadOnlyList<OptOutChangeResponseItem>>>().Object;
                 });
 
-            Response<OptOutChangeResponse> actualResponse = await mockClient.Object.AddAsync(expectedFrom, expectedTo, cancellationToken);
+            Response<IReadOnlyList<OptOutChangeResponseItem>> actualResponse = await mockClient.Object.AddAsync(expectedFrom, expectedTo, cancellationToken);
 
             mockClient.Verify(callExpression, Times.Once());
             Assert.AreEqual(expectedResponse, actualResponse);
@@ -119,7 +118,7 @@ public async Task AddAsyncOverload_PassesToGeneratedOne(string expectedFrom, IEn
         public void AddOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<string> expectedTo)
         {
             Mock<OptOutsClient> mockClient = new Mock<OptOutsClient>() { CallBase = true };
-            Response<OptOutChangeResponse>? expectedResponse = default;
+            Response<IReadOnlyList<OptOutChangeResponseItem>>? expectedResponse = default;
             CancellationToken cancellationToken = new CancellationTokenSource().Token;
             var callExpression = BuildExpression(x => x.Add(It.IsAny<string>(), It.IsAny<IEnumerable<string>>(), It.IsAny<CancellationToken>()));
 
@@ -130,10 +129,10 @@ public void AddOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<st
                     Assert.AreEqual(expectedFrom, from);
                     Assert.AreEqual(expectedTo, to);
                     Assert.AreEqual(cancellationToken, token);
-                    return expectedResponse = new Mock<Response<OptOutChangeResponse>>().Object;
+                    return expectedResponse = new Mock<Response<IReadOnlyList<OptOutChangeResponseItem>>>().Object;
                 });
 
-            Response<OptOutChangeResponse> actualResponse = mockClient.Object.Add(expectedFrom, expectedTo, cancellationToken);
+            Response<IReadOnlyList<OptOutChangeResponseItem>> actualResponse = mockClient.Object.Add(expectedFrom, expectedTo, cancellationToken);
 
             mockClient.Verify(callExpression, Times.Once());
             Assert.AreEqual(expectedResponse, actualResponse);
@@ -143,7 +142,7 @@ public void AddOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<st
         public async Task RemoveAsyncOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<string> expectedTo)
         {
             Mock<OptOutsClient> mockClient = new Mock<OptOutsClient>() { CallBase = true };
-            Response<OptOutChangeResponse>? expectedResponse = default;
+            Response<IReadOnlyList<OptOutChangeResponseItem>>? expectedResponse = default;
             CancellationToken cancellationToken = new CancellationTokenSource().Token;
             var callExpression = BuildExpression(x => x.RemoveAsync(It.IsAny<string>(), It.IsAny<IEnumerable<string>>(), It.IsAny<CancellationToken>()));
 
@@ -154,10 +153,10 @@ public async Task RemoveAsyncOverload_PassesToGeneratedOne(string expectedFrom,
                     Assert.AreEqual(expectedFrom, from);
                     Assert.AreEqual(expectedTo, to);
                     Assert.AreEqual(cancellationToken, token);
-                    return expectedResponse = new Mock<Response<OptOutChangeResponse>>().Object;
+                    return expectedResponse = new Mock<Response<IReadOnlyList<OptOutChangeResponseItem>>>().Object;
                 });
 
-            Response<OptOutChangeResponse> actualResponse = await mockClient.Object.RemoveAsync(expectedFrom, expectedTo, cancellationToken);
+            Response<IReadOnlyList<OptOutChangeResponseItem>> actualResponse = await mockClient.Object.RemoveAsync(expectedFrom, expectedTo, cancellationToken);
 
             mockClient.Verify(callExpression, Times.Once());
             Assert.AreEqual(expectedResponse, actualResponse);
@@ -167,7 +166,7 @@ public async Task RemoveAsyncOverload_PassesToGeneratedOne(string expectedFrom,
         public void RemoveOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable<string> expectedTo)
         {
             Mock<OptOutsClient> mockClient = new Mock<OptOutsClient>() { CallBase = true };
-            Response<OptOutChangeResponse>? expectedResponse = default;
+            Response<IReadOnlyList<OptOutChangeResponseItem>>? expectedResponse = default;
             CancellationToken cancellationToken = new CancellationTokenSource().Token;
             var callExpression = BuildExpression(x => x.Remove(It.IsAny<string>(), It.IsAny<IEnumerable<string>>(), It.IsAny<CancellationToken>()));
 
@@ -178,10 +177,10 @@ public void RemoveOverload_PassesToGeneratedOne(string expectedFrom, IEnumerable
                     Assert.AreEqual(expectedFrom, from);
                     Assert.AreEqual(expectedTo, to);
                     Assert.AreEqual(cancellationToken, token);
-                    return expectedResponse = new Mock<Response<OptOutChangeResponse>>().Object;
+                    return expectedResponse = new Mock<Response<IReadOnlyList<OptOutChangeResponseItem>>>().Object;
                 });
 
-            Response<OptOutChangeResponse> actualResponse = mockClient.Object.Remove(expectedFrom, expectedTo, cancellationToken);
+            Response<IReadOnlyList<OptOutChangeResponseItem>> actualResponse = mockClient.Object.Remove(expectedFrom, expectedTo, cancellationToken);
 
             mockClient.Verify(callExpression, Times.Once());
             Assert.AreEqual(expectedResponse, actualResponse);
diff --git a/sdk/communication/Azure.Communication.Sms/tests/SmsClientLiveTests.cs b/sdk/communication/Azure.Communication.Sms/tests/SmsClientLiveTests.cs
index 6ca4be841d952..77b83a6296ec2 100644
--- a/sdk/communication/Azure.Communication.Sms/tests/SmsClientLiveTests.cs
+++ b/sdk/communication/Azure.Communication.Sms/tests/SmsClientLiveTests.cs
@@ -10,6 +10,7 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using NUnit.Framework;
+using Azure.Communication.Sms.Models;
 
 namespace Azure.Communication.Sms.Tests
 {
@@ -31,8 +32,8 @@ public async Task SendingSmsMessage()
                    message: "Hi");
                 SmsSendResult result = response.Value;
                 Console.WriteLine($"Sms id: {result.MessageId}");
-                AssertHappyPath(result);
-                AssertRawResponseHappyPath(response.GetRawResponse().ContentStream ?? new MemoryStream());
+                AssertSmsSendingHappyPath(result);
+                AssertSmsSendingRawResponseHappyPath(response.GetRawResponse().ContentStream ?? new MemoryStream());
             }
             catch (RequestFailedException ex)
             {
@@ -57,8 +58,8 @@ public async Task SendingSmsMessageUsingTokenCredential()
                    message: "Hi");
                 SmsSendResult result = response.Value;
                 Console.WriteLine($"Sms id: {result.MessageId}");
-                AssertHappyPath(result);
-                AssertRawResponseHappyPath(response.GetRawResponse().ContentStream ?? new MemoryStream());
+                AssertSmsSendingHappyPath(result);
+                AssertSmsSendingRawResponseHappyPath(response.GetRawResponse().ContentStream ?? new MemoryStream());
             }
             catch (RequestFailedException ex)
             {
@@ -110,11 +111,11 @@ public async Task SendingSmsMessageToGroupWithOptions()
                        Tag = "marketing", // custom tags
                        DeliveryReportTimeoutInSeconds = 90 // OPTIONAL
                    });
-                AssertRawResponseHappyPath(response.GetRawResponse().ContentStream ?? new MemoryStream());
+                AssertSmsSendingRawResponseHappyPath(response.GetRawResponse().ContentStream ?? new MemoryStream());
                 foreach (SmsSendResult result in response.Value)
                 {
                     Console.WriteLine($"Sms id: {result.MessageId}");
-                    AssertHappyPath(result);
+                    AssertSmsSendingHappyPath(result);
                 }
             }
             catch (RequestFailedException ex)
@@ -143,15 +144,15 @@ public async Task SendingTwoSmsMessages()
                    to: TestEnvironment.ToPhoneNumber,
                    message: "Hi");
 
-                AssertRawResponseHappyPath(firstMessageResponse.GetRawResponse().ContentStream ?? new MemoryStream());
-                AssertRawResponseHappyPath(secondMessageResponse.GetRawResponse().ContentStream ?? new MemoryStream());
+                AssertSmsSendingRawResponseHappyPath(firstMessageResponse.GetRawResponse().ContentStream ?? new MemoryStream());
+                AssertSmsSendingRawResponseHappyPath(secondMessageResponse.GetRawResponse().ContentStream ?? new MemoryStream());
 
                 SmsSendResult firstMessageResult = firstMessageResponse.Value;
                 SmsSendResult secondMessageResult = secondMessageResponse.Value;
 
                 Assert.AreNotEqual(firstMessageResult.MessageId, secondMessageResult.MessageId);
-                AssertHappyPath(firstMessageResult);
-                AssertHappyPath(secondMessageResult);
+                AssertSmsSendingHappyPath(firstMessageResult);
+                AssertSmsSendingHappyPath(secondMessageResult);
             }
             catch (RequestFailedException ex)
             {
@@ -203,14 +204,134 @@ public async Task SendingSmsToNullNumberShouldThrow()
             Assert.Fail("SendAsync should have thrown an exception.");
         }
 
-        private void AssertHappyPath(SmsSendResult sendResult)
+        [Test]
+        public async Task CheckOptOutFromNullNumberShouldThrow()
+        {
+            SmsClient client = CreateSmsClient();
+            try
+            {
+                IEnumerable<string>? to = new string[] { TestEnvironment.ToPhoneNumber };
+                Response<IReadOnlyList<OptOutResponseItem>> result = await client.OptOuts.CheckAsync(
+                    from: null,
+                    to: to);
+            }
+            catch (ArgumentNullException ex)
+            {
+                Assert.AreEqual("from", ex.ParamName);
+                return;
+            }
+            Assert.Fail("CheckAsync should have thrown an exception.");
+        }
+
+        [Test]
+        public async Task CheckOptOutToNullNumberShouldThrow()
+        {
+            SmsClient client = CreateSmsClient();
+            try
+            {
+                IEnumerable<string>? to = null;
+                Response<IReadOnlyList<OptOutResponseItem>> result = await client.OptOuts.CheckAsync(
+                    from: TestEnvironment.FromPhoneNumber,
+                    to: to);
+            }
+            catch (ArgumentNullException ex)
+            {
+                Assert.AreEqual("to", ex.ParamName);
+                return;
+            }
+            Assert.Fail("CheckAsync should have thrown an exception.");
+        }
+
+        [Test]
+        public async Task CheckOptOutToCollectionContainingNullShouldThrow()
+        {
+            SmsClient client = CreateSmsClient();
+            try
+            {
+#pragma warning disable CS8625 // Cannot convert null literal to non-nullable reference type.
+                IEnumerable<string>? to = new string[]
+                {
+                    TestEnvironment.ToPhoneNumber,
+                    null
+                };
+#pragma warning restore CS8625 // Cannot convert null literal to non-nullable reference type.
+
+                Response<IReadOnlyList<OptOutResponseItem>> result = await client.OptOuts.CheckAsync(
+                    from: TestEnvironment.FromPhoneNumber,
+                    to: to);
+            }
+            catch (ArgumentNullException ex)
+            {
+                Assert.AreEqual("to", ex.ParamName);
+                return;
+            }
+            Assert.Fail("CheckAsync should have thrown an exception.");
+        }
+
+        [Test]
+        public async Task AddOptOutEndpointShouldMarkRecipientAsOptedOut()
+        {
+            SmsClient client = CreateSmsClient();
+            try
+            {
+                IEnumerable<string>? to = new[] { TestEnvironment.ToPhoneNumber };
+
+                Response<IReadOnlyList<OptOutChangeResponseItem>> addResult = await client.OptOuts.AddAsync(
+                    from: TestEnvironment.FromPhoneNumber,
+                    to: to);
+
+                Response<IReadOnlyList<OptOutResponseItem>> checkResult = await client.OptOuts.CheckAsync(
+                  from: TestEnvironment.FromPhoneNumber,
+                  to: to);
+
+                Assert.IsTrue(checkResult.Value[0].IsOptedOut);
+            }
+            catch (Exception ex)
+            {
+                Assert.Fail("Exception should not have been thrown.");
+                Console.WriteLine(ex);
+                return;
+            }
+        }
+
+        [Test]
+        public async Task RemoveOptOutEndpointShouldMarkRecipientAsOptedIn()
+        {
+            SmsClient client = CreateSmsClient();
+            try
+            {
+                IEnumerable<string>? to = new[] { TestEnvironment.ToPhoneNumber };
+
+                Response<IReadOnlyList<OptOutChangeResponseItem>> addResult = await client.OptOuts.AddAsync(
+                    from: TestEnvironment.FromPhoneNumber,
+                    to: to);
+
+                Response<IReadOnlyList<OptOutChangeResponseItem>> removeResult = await client.OptOuts.RemoveAsync(
+                    from: TestEnvironment.FromPhoneNumber,
+                    to: to);
+
+                Response<IReadOnlyList<OptOutResponseItem>> checkResult = await client.OptOuts.CheckAsync(
+                    from: TestEnvironment.FromPhoneNumber,
+                    to: to);
+
+                Assert.IsFalse(checkResult.Value[0].IsOptedOut);
+            }
+            catch (Exception ex)
+            {
+                Assert.Fail("Exception should not have been thrown.");
+                Console.WriteLine(ex);
+                return;
+            }
+        }
+
+        private void AssertSmsSendingHappyPath(SmsSendResult sendResult)
         {
             Assert.True(sendResult.Successful);
             Assert.AreEqual(202, sendResult.HttpStatusCode);
             Assert.IsFalse(string.IsNullOrWhiteSpace(sendResult.MessageId));
         }
 
-        private void AssertRawResponseHappyPath(Stream contentStream)
+        private void AssertSmsSendingRawResponseHappyPath(Stream contentStream)
         {
             if (contentStream.Length > 0)
             {