Facing this error related to azure communication services >Action failed, Transport url is not valid or web socket server is not operational.

Question

Facing this error related to azure communication services >Action failed, Transport url is not valid or web socket server is not operational.

Abhishek Pandey 0

Hello World

Client connected to WebSocket

[2025-09-18 21:34:20,574] INFO in main: Received Event:-> Microsoft.Communication.ParticipantsUpdated, Correlation Id:-> c38c9b63-<removed PII>, CallConnectionId:-> 07004280-<removed PII>

[2025-09-18 21:34:20,577] INFO in main: Received Event:-> Microsoft.Communication.MediaStreamingFailed, Correlation Id:-> c38c9b63-<removed PII>, CallConnectionId:-> 07004280-<removed PII>

[2025-09-18 21:34:20,577] INFO in main: Code:->400, Subcode:-> 8581

[2025-09-18 21:34:20,578] INFO in main: Message:->Action failed, Transport url is not valid or web socket server is not operational.

[2025-09-18 21:34:20 +0530] [11208] [INFO] 127.0.0.1:58754 POST /api/callbacks/c978d234-70ce-4339-b92d-c15411766216 1.1 200 - 8440

[2025-09-18 21:34:20 +0530] [11208] [INFO] 127.0.0.1:58753 POST /api/callbacks/c978d234-70ce-4339-b92d-c15411766216 1.1 200 - 9434

[2025-09-18 21:34:20,588] INFO in main: Received Event:-> Microsoft.Communication.CallConnected, Correlation Id:-> c38c9b63-<removed PII>5, CallConnectionId:-> 07004280-<removed PII>

[2025-09-18 21:34:20,880] INFO in main: MediaStreamingSubscription:--> {'additional_properties': {}, 'id': '5d93435e-8f57-4271-b7ec-ccfbf8b19265', 'state': 'inactive', 'subscribed_content_types': ['audio']}

[2025-09-18 21:34:20,882] INFO in main: Received CallConnected event for connection id: 07004280-2a11-4702-b966-fb4af29a4fe1

[2025-09-18 21:34:20,882] INFO in main: CORRELATION ID:--> c38c9b63-<removed PII>

[2025-09-18 21:34:20,883] INFO in main: CALL CONNECTION ID:--> 07004280-<removed PII>

[2025-09-18 21:34:20 +0530] [11208] [INFO] 127.0.0.1:58756 POST /api/callbacks/c978d234-70ce-4339-b92d-c15411766216 1.1 200 - 297788

[2025-09-18 21:34:22,958] INFO in main: Received Event:-> Microsoft.Communication.ParticipantsUpdated, Correlation Id:-> c38c9b63-<removed PII>, CallConnectionId:-> 07004280-<removed PII>

[2025-09-18 21:34:22 +0530] [11208] [INFO] 127.0.0.1:58758 POST /api/callbacks/c978d234-70ce-4339-b92d-c15411766216 1.1 200 - 3295

[2025-09-18 21:34:59,416] INFO in main: Received Event:-> Microsoft.Communication.CallDisconnected, Correlation Id:-> c38c9b63-<removed PII>, CallConnectionId:-> 07004280-<removed PII>

[2025-09-18 21:34:59 +0530] [11208] [INFO] 127.0.0.1:58774 POST /api/callbacks/c978d234-70ce-4339-b92d-c15411766216 1.1 200 - 4095

facing this errors found no solution anywhere we are trying to run the repo code of acs
link : https://github.com/Azure-Samples/communication-services-python-quickstarts/tree/main/callautomation-azure-openai-voice

Please help me with this

Praneeth Maddali 12,505 Reputation points Microsoft External Staff Moderator

2025-09-25T12:31:32.4+00:00

Hi Abhishek Pandey
Just following up to see if your issue has been resolved or if you had a chance to review my earlier comment?
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This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.

1 answer

Your answer

Praneeth Maddali 12,505 Reputation points Microsoft External Staff Moderator

2025-09-25T12:31:32.4+00:00

Hi Abhishek Pandey
Just following up to see if your issue has been resolved or if you had a chance to review my earlier comment?
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.

Answer 1

Praneeth Maddali 12,505 Microsoft External Staff Moderator

Hi @Abhishek Pandey

Thank you for reaching out regarding the error you're encountering with the Azure Communication Services (ACS) Call Automationquickstart: "Action failed, Transport url is not valid or web socket server is not operational" (HTTP 400, Subcode 8581). After reviewing the logs you shared, we found that this issue happens because the WebSocket server URL (transport_url) used for media streaming in your setup (from this GitHub repository) is either invalid or not publicly accessible.

The call seems to connect successfully (CallConnected), but media streaming does not work because of the WebSocket configuration. This is a frequent issue when running the sample locally, and we've provided a solution below to help resolve it.

Please follow below steps to the Solution:

Use ngrok to expose your local server:
- Download and install ngrok from ngrok.com (you'll need to create a free account).
- Start your local server, such as the FastAPI app in app.py, usually running on port 8000.
- In a terminal, run ngrok http 8000 to generate a public URL (for example, https://abc123.ngrok-free.app).

Please update the Transport URL.

Please update the transport_url in your code (most likely where StartMediaStreamingOptions is configured) to use the ngrok WebSocket endpoint.

     from azure.communication.callautomation import StartMediaStreamingOptions
     streaming_options = StartMediaStreamingOptions(
         transport_url="wss://<your-ngrok-url>.ngrok-free.app/ws/media",
         subscribed_content_types=['audio']
     )

Make sure the WebSocket path (/ws/media) aligns with your server’s configuration.

Verify the Setup:
- Restart your server and initiate a new call through the quickstart.
- Review the logs to confirm that the MediaStreamingSubscription state is set to active, rather than inactive as previously shown.
- If the issue continues, check that the WebSocket URL is accessible using a tool like wscat or a browser.
- If problems persist:

Make sure ngrok is running and that the URL can be accessed from outside your network.
Review your ACS resource’s network settings in the Azure Portal to confirm there are no firewall rules blocking ngrok domains.
Turn on diagnostics by going to Azure Portal > Communication Services > Your resource > Monitoring > Diagnostic settings.

Reference :

https://learn.microsoft.com/en-us/azure/communication-services/resources/troubleshooting/voice-video-calling/troubleshooting-codes?pivots=calling

https://learn.microsoft.com/en-us/azure/communication-services/how-tos/call-automation/real-time-transcription-tutorial?pivots=programming-language-javascript

Kindly let us know if the above helps or you need further assistance on this issue.

Please "upvote" if the information helped you. This will help us and others in the community as well.

Abhishek Pandey 0

hi Praneeth
The issue still persists even after using ngrok please look into some options and guide me further how I can resolve it as this has become a blocker for us

incoming_call_context=event.data['incomingCallContext']
                guid =uuid.uuid4()
                query_parameters = urlencode({"callerId": caller_id})
                callback_uri = f"{CALLBACK_EVENTS_URI}/{guid}?{query_parameters}"
                
                parsed_url = urlparse(CALLBACK_EVENTS_URI)
                websocket_url = urlunparse(('wss',parsed_url.netloc,'/ws','', '', ''))

                app.logger.info("callback url: %s",  callback_uri)
                app.logger.info("websocket url: %s",  websocket_url)

                media_streaming_options = MediaStreamingOptions(
                        transport_url=websocket_url,
                        transport_type=StreamingTransportType.WEBSOCKET,
                        content_type=MediaStreamingContentType.AUDIO,
                        audio_channel_type=MediaStreamingAudioChannelType.MIXED,
                        start_media_streaming=True,
                        enable_bidirectional=True,
                        audio_format=AudioFormat.PCM24_K_MONO)
                
                answer_call_result = await acs_client.answer_call(incoming_call_context=incoming_call_context,
                                                            operation_context="incomingCall",
                                                            callback_url=callback_uri, 
                                                            media_streaming=media_streaming_options)
                app.logger.info("Answered call for connection id: %s",
                                answer_call_result.call_connection_id)
            return Response(status=200)

Praneeth Maddali 12,505 Reputation points Microsoft External Staff Moderator

2025-09-29T02:16:49.25+00:00
Hi @Abhishek Pandey

Thank you for your follow-up and for sharing the additional code snippet—it’s very useful for further troubleshooting. I’m sorry that setting up ngrok didn’t resolve the “Action failed, Transport url is not valid or web socket server is not operational” error (HTTP 400, Subcode 8581) in the Microsoft.Communication.MediaStreamingFailed event. This is a frequent issue with the callautomation-azure-openai-voice quickstart repo during local development, since it requires a public WebSocket server for audio streaming with Azure OpenAI integration.

From your code, the problem appears to be with how the websocket_url is created for MediaStreamingOptions. In detail:

The callback_uri for call events is correctly formed using the full CALLBACK_EVENTS_URI (such as https://your-ngrok-url.ngrok-free.app/api/callbacks/{guid}?callerId={caller_id}).

However, the websocket_url uses only the netloc (domain/host) from CALLBACK_EVENTS_URI, resulting in a URL like wss://your-ngrok-url.ngrok-free.app/ws, which lacks the correct path. This causes issues because:

Azure Communication Services (ACS) tries to connect but fails validation or connection (subcode 8581 means “Invalid Stream URL”).

The FastAPI app’s WebSocket endpoint is mounted at /ws, but the OpenAI integration may use a more specific subpath like /ws/media or /ws/openai, depending on the session handler.

If the path doesn’t match the server’s route, the WebSocket handshake fails, so the streaming subscription stays inactive, as you saw in your logs.

This mismatch prevents ACS from connecting to the WebSocket for media streaming, even though the call itself connects successfully (CallConnected event).

Suggested Solution: Correct the WebSocket URL construction and check the setup.

To address this, we'll update the code to construct the websocket_url using the complete ngrok base (including the scheme, netloc, and correct path), make sure the WebSocket route matches the repository's setup, and include validation steps. This should enable your media streaming and resolve the Azure OpenAI voice integration issue.

Step 1: Update your code to use the correct WebSocket URL.

In your incoming call handler (such as in app.py), make sure to set the websocket_url using the ngrok-exposed base URL and add the correct WebSocket path. Typically, the repository uses /ws as the base route for media, but verify this by checking the FastAPI mount in app.py (for example, app.mount("/ws", app=websocket_app)).

Here's the updated code snippet:

from urllib.parse import urlparse, urlunparse from azure.communication.callautomation import MediaStreamingOptions, StreamingTransportType, MediaStreamingContentType, MediaStreamingAudioChannelType, AudioFormat import uuid from urllib.parse import urlencode # ... (your existing imports and setup) async def handle_incoming_call(event): incoming_call_context = event.data['incomingCallContext'] guid = uuid.uuid4() query_parameters = urlencode({"callerId": caller_id}) callback_uri = f"{CALLBACK_EVENTS_URI}/{guid}?{query_parameters}" app.logger.info("callback url: %s", callback_uri) # Parse the ngrok-exposed base URL (e.g., https://abc123.ngrok-free.app) parsed_url = urlparse(CALLBACK_EVENTS_URI) # Build WebSocket URL with correct scheme (wss) and path (/ws or /ws/media based on your app's route) # Check app.py for the exact WebSocket path; it's often /ws for media sessions websocket_path = "/ws" # Update to "/ws/media" if your OpenAI handler uses a subpath websocket_url = urlunparse(('wss', parsed_url.netloc, websocket_path, '', '', '')) app.logger.info("websocket url: %s", websocket_url) # Ensure bidirectional is enabled for OpenAI voice integration media_streaming_options = MediaStreamingOptions( transport_url=websocket_url, transport_type=StreamingTransportType.WEBSOCKET, content_type=MediaStreamingContentType.AUDIO, audio_channel_type=MediaStreamingAudioChannelType.MIXED, # Use 'unmixed' if per-participant streams are needed start_media_streaming=True, enable_bidirectional=True, audio_format=AudioFormat.PCM24_K_MONO ) answer_call_result = await acs_client.answer_call( incoming_call_context=incoming_call_context, operation_context="incomingCall", callback_url=callback_uri, media_streaming=media_streaming_options ) app.logger.info("Answered call for connection id: %s", answer_call_result.call_connection_id) return Response(status=200)

Key Changes:

Use parsed_url.netloc (for example, abc123.ngrok-free.app) and set the path to match your server’s WebSocket mount. Check app.py for app.mount("/ws", ...) or similar configurations.

If the repository uses a subpath such as /ws/media for OpenAI streaming, make sure to update websocket_path accordingly. You can search the repository for "ws/media" or review the WebSocket handler for details.

Log the websocket_url to verify it appears as wss://abc123.ngrok-free.app/ws.

Step 2: Restart and Set Up ngrok Properly

Stop your local server and ngrok.

Restart your FastAPI app using: uvicorn app:app --host 0.0.0.0 --port 8000 --reload (make sure it's set to 0.0.0.0 for ngrok access).

Open a new terminal and start ngrok: ngrok http 8000. Take note of the HTTPS forwarding URL (for example, https://abc123.ngrok-free.app).

Set your CALLBACK_EVENTS_URI environment variable to the ngrok URL (e.g., export CALLBACK_EVENTS_URI="https://abc123.ngrok-free.app").

Restart the app so it uses the updated URI.

Run a test call using the quickstart script.

Step 3: Validate the WebSocket Endpoint
Test accessibility: Use a WebSocket client such as wscat (install with npm install -g wscat) to connect: wscat -c wss://abc123.ngrok-free.app/ws.

If you see "connected," the endpoint is live. You can send a test JSON message like {"Kind": "SessionCreated"} to simulate repo traffic.

If the connection fails (for example, you get a 404 or connection refused), the path may be incorrect—check app.py for the correct mount path.

Watch ngrok inspect for incoming WebSocket connections from ACS IPs during a call.

Check logs for:

MediaStreamingSubscription state changing to active.

No MediaStreamingFailed event.

Successful Azure OpenAI session creation (such as "Session Created Message Session Id: ...").

Step 4: Additional Checks if It Still Fails

Firewall/Network: In the Azure Portal, go to Communication Services > Your Resource > Networking. Make sure "Allow public access" is enabled or add ngrok’s IP range (since ngrok uses dynamic IPs, public access is usually safest). If possible, try testing from a different network.

Repo-Specific: This sample integrates with Azure OpenAI Realtime API, which needs the WebSocket to handle specific messages like SessionCreated. If the handler isn’t working, streaming will fail. Try cloning the repo again and compare your app.py WebSocket logic.

Alternative Tunneling: If ngrok is unreliable (free tier limits can cause issues), use dev tunnels with the VS Code extension or run: devtunnel host -p 8000 --allow-anonymous.

Enable Diagnostics: In the Azure Portal, go to Communication Services > Your Resource > Monitoring > Diagnostic settings. Send logs to Log Analytics and search for "MediaStreamingFailed" for more details.

Version Check: Make sure you have the latest version of azure-communication-callautomation (check with pip show azure-communication-callautomation). Update if it’s below 1.0.0.

Reference:

https://learn.microsoft.com/en-us/azure/communication-services/how-tos/call-automation/audio-streaming-quickstart?pivots=programming-language-python

https://learn.microsoft.com/en-us/dotnet/api/azure.communication.callautomation.mediastreamingoptions?view=azure-dotnet

Kindly let us know if the above helps or you need further assistance on this issue.

Please "upvote" if the information helped you. This will help us and others in the community as well.