diff --git a/samples/middle-tier/python-fastapi/rt-middle-tier/main.py b/samples/middle-tier/python-fastapi/rt-middle-tier/main.py
index b1db119..4be2467 100644
--- a/samples/middle-tier/python-fastapi/rt-middle-tier/main.py
+++ b/samples/middle-tier/python-fastapi/rt-middle-tier/main.py
@@ -1,23 +1,26 @@
+import asyncio
+import json
+import os
+import uuid
+from typing import Literal, TypedDict, Union
+
+import uvicorn
+from azure.core.credentials import AzureKeyCredential
+from azure.identity import DefaultAzureCredential
+from dotenv import load_dotenv
 from fastapi import FastAPI, WebSocket
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.websockets import WebSocketState
-import uvicorn
-import uuid
-import json
-from typing import Union, Literal, TypedDict
-import asyncio
 from loguru import logger
-import os
-from dotenv import load_dotenv
-from azure.identity import DefaultAzureCredential
-from azure.core.credentials import AzureKeyCredential
 from rtclient import (
     InputAudioTranscription,
+    InputTextContentPart,
+    RTAudioContent,
     RTClient,
-    ServerVAD,
     RTInputAudioItem,
     RTResponse,
-    RTAudioContent,
+    ServerVAD,
+    UserMessageItem,
 )
 
 load_dotenv()
@@ -71,11 +74,20 @@ def _initialize_client(self, backend: str | None):
         self.logger.debug(f"Initializing RT client with backend: {backend}")
 
         if backend == "azure":
-            return RTClient(
-                url=os.getenv("AZURE_OPENAI_ENDPOINT"),
-                token_credential=DefaultAzureCredential(),
-                deployment=os.getenv("AZURE_OPENAI_DEPLOYMENT"),
-            )
+            azure_openai_api_key = os.getenv("AZURE_OPENAI_API_KEY")
+            # If the Azure OpenAI API key is not provided, use the DefaultAzureCredential
+            if not azure_openai_api_key:
+                return RTClient(
+                    url=os.getenv("AZURE_OPENAI_ENDPOINT"),
+                    token_credential=DefaultAzureCredential(),
+                    azure_deployment=os.getenv("AZURE_OPENAI_DEPLOYMENT"),
+                )
+            else:
+                return RTClient(
+                    url=os.getenv("AZURE_OPENAI_ENDPOINT"),
+                    key_credential=AzureKeyCredential(azure_openai_api_key),
+                    azure_deployment=os.getenv("AZURE_OPENAI_DEPLOYMENT"),
+                )
         return RTClient(
             key_credential=AzureKeyCredential(os.getenv("OPENAI_API_KEY")),
             model=os.getenv("OPENAI_MODEL"),
@@ -91,7 +103,7 @@ async def initialize(self):
         self.logger.debug("Configuring realtime session")
         await self.client.configure(
             modalities={"text", "audio"},
-            voice="coral",
+            voice="alloy",
             input_audio_format="pcm16",
             input_audio_transcription=InputAudioTranscription(model="whisper-1"),
             turn_detection=ServerVAD(),
@@ -120,13 +132,13 @@ async def handle_text_message(self, message: str):
 
             if parsed["type"] == "user_message":
                 await self.client.send_item(
-                    {
-                        "type": "message",
-                        "role": "user",
-                        "content": [{"type": "input_text", "text": parsed["text"]}],
-                    }
+                    UserMessageItem(
+                        content=[InputTextContentPart(text=parsed["text"])],
+                    )
                 )
+                # Trigger the response generation and wait for the response
                 await self.client.generate_response()
+
                 self.logger.debug("User message processed successfully")
         except Exception as error:
             self.logger.error(f"Failed to process user message: {error}")