Azure AI Foundry Voice Live SIP: Inbound Call Fails with 502 Error and No Webhook Delivery

Problem description

I am experiencing an issue with my Azure AI Foundry Voice Live SIP inbound setup. When an inbound call from my SIP carrier reaches the service, it successfully completes digest authentication but then receives a 502 Internal Server Error. Additionally, no webhook request is ever received at my configured endpoint. I am seeking help to understand why the call fails after authentication and why the webhook is not triggered.

Environment

Azure AI Services resource with Voice Live SIP in East US 2, using generic_sip provider, with inbound calling configured, SIP digest authentication enabled, and webhook registration active.

What I've already tried

I verified that the SIP configuration was set up according to the official Voice Live SIP guidance, and API calls to retrieve the configuration returned a 200 OK. I confirmed that inbound SIP was enabled, digest authentication was configured with a password, the carrier IP allowlist was correctly set, and the webhook was registered and subscribed to all event types. I tested inbound calls from the SIP carrier and a direct TLS test client; in both cases, digest authentication succeeded, but the call failed with a 502 error and no webhook request was observed. I also checked that the webhook endpoint is reachable and responds correctly to manual POST requests, and that the configuration has not changed recently.

Current status

Currently, the SIP configuration appears correct, and the call reaches the service but fails after digest authentication with a 502 error. No webhook requests are received at the endpoint. I am looking for guidance on how to troubleshoot further, particularly on what could cause the 502 error after authentication and why the webhook is not triggered, despite being registered and active.