diff --git a/changelog.md b/changelog.md
index 461d61ec..2c6e3c50 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,3 +1,8 @@
+# Microsoft 365 Agents SDK for Python - Release Notes v1.4.0 (Unreleased)
+
+## New Models & APIs
+- **Regionalized UserTokenClient Support**: Added optional argument to `CloudAdapter` to configure Token Service endpoint used by `RestChannelServiceClientFactory` when creating `UserTokenClient` instances. 
+
 # Microsoft 365 Agents SDK for Python - Release Notes v1.3.0
 
 **Release Date:** 2026-07-30
diff --git a/dev/integration/tests/adapter/__init__.py b/dev/integration/tests/adapter/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/dev/integration/tests/adapter/test_aiohttp_cloud_adapter.py b/dev/integration/tests/adapter/test_aiohttp_cloud_adapter.py
new file mode 100644
index 00000000..154b6529
--- /dev/null
+++ b/dev/integration/tests/adapter/test_aiohttp_cloud_adapter.py
@@ -0,0 +1,52 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+from typing import cast
+
+import pytest
+
+from microsoft_agents.activity import Activity, ConversationAccount
+from microsoft_agents.hosting.aiohttp import CloudAdapter
+from microsoft_agents.hosting.core import TurnContext
+from microsoft_agents.hosting.core.authorization import ClaimsIdentity, Connections
+from microsoft_agents.hosting.core.connector.client import UserTokenClient
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "token_service_endpoint",
+    [
+        "https://europe.api.botframework.com",
+        "https://unitedstates.api.botframework.com",
+        "https://india.api.botframework.com",
+    ],
+)
+async def test_cloud_adapter_configures_user_token_client_endpoint(
+    token_service_endpoint: str,
+):
+    adapter = CloudAdapter(
+        connection_manager=cast(Connections, object()),
+        channel_service_client_factory_options={
+            "token_service_endpoint": token_service_endpoint
+        },
+    )
+    identity = ClaimsIdentity({"aud": "test-app-id"}, True)
+    context = TurnContext(
+        adapter,
+        Activity(
+            type="message",
+            conversation=ConversationAccount(id="conversation-id"),
+        ),
+        identity,
+    )
+
+    client = await adapter._channel_service_client_factory.create_user_token_client(
+        context,
+        identity,
+        use_anonymous=True,
+    )
+    assert isinstance(client, UserTokenClient)
+    try:
+        assert str(client.client._base_url) == f"{token_service_endpoint}/"
+    finally:
+        await client.close()
diff --git a/dev/integration/tests/adapter/test_fastapi_cloud_adapter.py b/dev/integration/tests/adapter/test_fastapi_cloud_adapter.py
new file mode 100644
index 00000000..4c79c1a7
--- /dev/null
+++ b/dev/integration/tests/adapter/test_fastapi_cloud_adapter.py
@@ -0,0 +1,52 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+from typing import cast
+
+import pytest
+
+from microsoft_agents.activity import Activity, ConversationAccount
+from microsoft_agents.hosting.core import TurnContext
+from microsoft_agents.hosting.core.authorization import ClaimsIdentity, Connections
+from microsoft_agents.hosting.core.connector.client import UserTokenClient
+from microsoft_agents.hosting.fastapi import CloudAdapter
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "token_service_endpoint",
+    [
+        "https://europe.api.botframework.com",
+        "https://unitedstates.api.botframework.com",
+        "https://india.api.botframework.com",
+    ],
+)
+async def test_cloud_adapter_configures_user_token_client_endpoint(
+    token_service_endpoint: str,
+):
+    adapter = CloudAdapter(
+        connection_manager=cast(Connections, object()),
+        channel_service_client_factory_options={
+            "token_service_endpoint": token_service_endpoint
+        },
+    )
+    identity = ClaimsIdentity({"aud": "test-app-id"}, True)
+    context = TurnContext(
+        adapter,
+        Activity(
+            type="message",
+            conversation=ConversationAccount(id="conversation-id"),
+        ),
+        identity,
+    )
+
+    client = await adapter._channel_service_client_factory.create_user_token_client(
+        context,
+        identity,
+        use_anonymous=True,
+    )
+    assert isinstance(client, UserTokenClient)
+    try:
+        assert str(client.client._base_url) == f"{token_service_endpoint}/"
+    finally:
+        await client.close()
diff --git a/libraries/microsoft-agents-hosting-aiohttp/microsoft_agents/hosting/aiohttp/cloud_adapter.py b/libraries/microsoft-agents-hosting-aiohttp/microsoft_agents/hosting/aiohttp/cloud_adapter.py
index 234cd679..9ca08b5a 100644
--- a/libraries/microsoft-agents-hosting-aiohttp/microsoft_agents/hosting/aiohttp/cloud_adapter.py
+++ b/libraries/microsoft-agents-hosting-aiohttp/microsoft_agents/hosting/aiohttp/cloud_adapter.py
@@ -24,16 +24,20 @@ def __init__(
         *,
         connection_manager: Connections | None = None,
         channel_service_client_factory: ChannelServiceClientFactoryBase | None = None,
+        channel_service_client_factory_options: dict | None = None,
     ):
         """
         Initializes a new instance of the CloudAdapter class.
 
         :param connection_manager: Optional connection manager for OAuth.
-        :param channel_service_client_factory: The factory to use to create the channel service client.
+        :param channel_service_client_factory: Factory for creating channel service clients.
+        :param channel_service_client_factory_options: Optional dictionary of options to pass to the channel service client factory
+            This is only used if channel_service_client_factory is not provided and connection_manager is provided.
         """
         super().__init__(
             connection_manager=connection_manager,
             channel_service_client_factory=channel_service_client_factory,
+            channel_service_client_factory_options=channel_service_client_factory_options,
         )
 
     async def process(self, request: Request, agent: Agent) -> Optional[Response]:
diff --git a/libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/_http_adapter_base.py b/libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/_http_adapter_base.py
index e99b80b5..8add7c0c 100644
--- a/libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/_http_adapter_base.py
+++ b/libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/_http_adapter_base.py
@@ -34,12 +34,14 @@ def __init__(
         *,
         connection_manager: Connections | None = None,
         channel_service_client_factory: ChannelServiceClientFactoryBase | None = None,
+        channel_service_client_factory_options: dict | None = None,
     ):
         """Initialize the HTTP adapter.
 
-        Args:
-            connection_manager: Optional connection manager for OAuth.
-            channel_service_client_factory: Factory for creating channel service clients.
+        :param connection_manager: Optional connection manager for OAuth.
+        :param channel_service_client_factory: Factory for creating channel service clients.
+        :param channel_service_client_factory_options: Optional dictionary of options to pass to the channel service client factory
+            This is only used if channel_service_client_factory is not provided and connection_manager is provided.
         """
 
         async def on_turn_error(context: TurnContext, error: Exception):
@@ -67,7 +69,10 @@ async def on_turn_error(context: TurnContext, error: Exception):
                 raise ValueError(
                     "HttpAdapterBase.__init__: Either channel_service_client_factory or connection_manager must be provided."
                 )
-            factory = RestChannelServiceClientFactory(connection_manager)
+            factory = RestChannelServiceClientFactory(
+                connection_manager,
+                **(channel_service_client_factory_options or {}),
+            )
 
         super().__init__(factory)
 
diff --git a/libraries/microsoft-agents-hosting-fastapi/microsoft_agents/hosting/fastapi/cloud_adapter.py b/libraries/microsoft-agents-hosting-fastapi/microsoft_agents/hosting/fastapi/cloud_adapter.py
index 15f477fa..731ccb9c 100644
--- a/libraries/microsoft-agents-hosting-fastapi/microsoft_agents/hosting/fastapi/cloud_adapter.py
+++ b/libraries/microsoft-agents-hosting-fastapi/microsoft_agents/hosting/fastapi/cloud_adapter.py
@@ -25,16 +25,20 @@ def __init__(
         *,
         connection_manager: Connections | None = None,
         channel_service_client_factory: ChannelServiceClientFactoryBase | None = None,
+        channel_service_client_factory_options: dict | None = None,
     ):
         """
         Initializes a new instance of the CloudAdapter class.
 
         :param connection_manager: Optional connection manager for OAuth.
-        :param channel_service_client_factory: The factory to use to create the channel service client.
+        :param channel_service_client_factory: Factory for creating channel service clients.
+        :param channel_service_client_factory_options: Optional dictionary of options to pass to the channel service client factory
+            This is only used if channel_service_client_factory is not provided and connection_manager is provided.
         """
         super().__init__(
             connection_manager=connection_manager,
             channel_service_client_factory=channel_service_client_factory,
+            channel_service_client_factory_options=channel_service_client_factory_options,
         )
 
     async def process(self, request: Request, agent: Agent) -> Optional[Response]: