diff --git a/sdk/communication/azure-communication-chat/azure/communication/chat/_communication_identifier_serializer.py b/sdk/communication/azure-communication-chat/azure/communication/chat/_communication_identifier_serializer.py
index 6b08da1d07ea..13c103634137 100644
--- a/sdk/communication/azure-communication-chat/azure/communication/chat/_communication_identifier_serializer.py
+++ b/sdk/communication/azure-communication-chat/azure/communication/chat/_communication_identifier_serializer.py
@@ -31,7 +31,7 @@ def serialize_identifier(identifier):
         request_model = {"raw_id": identifier.raw_id}
 
         if identifier.kind and identifier.kind != CommunicationIdentifierKind.UNKNOWN:
-            request_model[identifier.kind] = dict(identifier.properties)
+            request_model[str(identifier.kind)] = dict(identifier.properties)  # type: ignore[assignment]
         return request_model
     except AttributeError:
         raise TypeError(  # pylint: disable=raise-missing-from
@@ -52,7 +52,7 @@ def deserialize_identifier(identifier_model):
     raw_id = identifier_model.raw_id
 
     if identifier_model.communication_user:
-        return CommunicationUserIdentifier(raw_id, raw_id=raw_id)
+        return CommunicationUserIdentifier(raw_id or "", raw_id=raw_id)
     if identifier_model.phone_number:
         return PhoneNumberIdentifier(identifier_model.phone_number.value, raw_id=raw_id)
     if identifier_model.microsoft_teams_user:
@@ -62,4 +62,4 @@ def deserialize_identifier(identifier_model):
             is_anonymous=identifier_model.microsoft_teams_user.is_anonymous,
             cloud=identifier_model.microsoft_teams_user.cloud,
         )
-    return UnknownIdentifier(raw_id)
+    return UnknownIdentifier(raw_id or "")
diff --git a/sdk/communication/azure-communication-chat/azure/communication/chat/_shared/policy.py b/sdk/communication/azure-communication-chat/azure/communication/chat/_shared/policy.py
index 1843d22e83a2..211f2ff0cfcf 100644
--- a/sdk/communication/azure-communication-chat/azure/communication/chat/_shared/policy.py
+++ b/sdk/communication/azure-communication-chat/azure/communication/chat/_shared/policy.py
@@ -66,7 +66,7 @@ def _sign_request(self, request):
         # Need URL() to get a correct encoded key value, from "%3A" to ":", when transport is in type AioHttpTransport.
         # There's a similar scenario in azure-storage-blob and azure-appconfiguration, the check logic is from there.
         try:
-            from yarl import URL
+            from yarl import URL  # type: ignore[import-not-found]
             from azure.core.pipeline.transport import (  # pylint:disable=non-abstract-transport-import
                 AioHttpTransport,
             )
diff --git a/sdk/communication/azure-communication-chat/azure/communication/chat/_utils.py b/sdk/communication/azure-communication-chat/azure/communication/chat/_utils.py
index c4dc8b52b098..0bc717f2486c 100644
--- a/sdk/communication/azure-communication-chat/azure/communication/chat/_utils.py
+++ b/sdk/communication/azure-communication-chat/azure/communication/chat/_utils.py
@@ -4,6 +4,10 @@
 # license information.
 # --------------------------------------------------------------------------
 
+from typing import Dict, List, Tuple, Optional
+from ._models import ChatParticipant
+from ._generated.models import ChatError
+
 
 def _to_utc_datetime(value):
     return value.strftime("%Y-%m-%dT%H:%M:%SZ")
@@ -24,7 +28,7 @@ class CommunicationErrorResponseConverter(object):
 
     @classmethod
     def convert(cls, participants, chat_errors):
-        # type: (...) -> list[(ChatThreadParticipant, ChatError)]
+        # type: (...) -> List[Tuple[Optional[ChatParticipant], ChatError]]
         """
         Util function to convert AddChatParticipantsResult.
 
@@ -41,12 +45,12 @@ def convert(cls, participants, chat_errors):
         """
 
         def create_dict(participants):
-            # type: (...) -> Dict(str, ChatThreadParticipant)
+            # type: (...) -> Dict[str, ChatParticipant]
             """
             Create dictionary of id -> ChatParticipant
 
-            :param list participants: list of ChatThreadParticipant
-            :return: Dictionary of id -> ChatThreadParticipant
+            :param list participants: list of ChatParticipant
+            :return: Dictionary of id -> ChatParticipant
             :rtype: dict
             """
             result = {}
diff --git a/sdk/communication/azure-communication-chat/pyproject.toml b/sdk/communication/azure-communication-chat/pyproject.toml
index 05ee5668ed6a..343877d67195 100644
--- a/sdk/communication/azure-communication-chat/pyproject.toml
+++ b/sdk/communication/azure-communication-chat/pyproject.toml
@@ -1,4 +1,4 @@
 [tool.azure-sdk-build]
-mypy = false
+mypy = true
 pyright = false
 type_check_samples = false