Is it possible to configure a custom SIP trunk in Genesys Cloud using a legacy 403 Forbidden error response from the provider’s registrar without triggering a permanent registration block in the Architect console? The current integration setup involves a direct SIP trunk connection to an on-premise PBX that utilizes strict digest authentication with a dynamic realm string. When the Genesys Cloud edge node attempts to register, the provider’s firewall returns a 403 Forbidden with a custom WWW-Authenticate header containing a non-standard ‘opaque’ parameter that Genesys Cloud’s SIP stack appears to reject as malformed. The logs in the System Logs tab show the initial REGISTER request is sent, followed immediately by the 403 response, and subsequent retries are spaced out exponentially, effectively halting inbound routing for that tenant. The SIP trunk configuration in Architect has the username, password, and display name configured exactly as provided by the telecom vendor, and the IP address of the edge node is whitelisted on the provider’s side. Despite verifying the credentials via an external SIP testing tool like SIPp, which successfully registers against the same endpoint, the Genesys Cloud integration fails to parse the challenge correctly. The issue seems to stem from the handling of the ‘qop’ parameter in the authentication challenge, where the provider sends ‘auth-int’ but Genesys Cloud expects ‘auth’. There is no documentation in the Genesys Cloud Help Center regarding custom handling of SIP digest authentication parameters or overriding the default User-Agent string that might be causing the provider’s legacy SIP proxy to flag the request as unauthorized. The environment is running the latest Genesys Cloud release, and the SIP trunk is configured with TLS enabled on port 5061. Debug logs from the edge node show the exact 403 response payload, but there is no option in the UI to inject custom headers or modify the digest calculation logic. This blocker is preventing any inbound calls from reaching the contact center queues, and the fallback to PSTN is not viable due to cost constraints. Has anyone encountered a similar issue with non-standard SIP digest challenges and found a workaround, such as using a BYOC edge connector or a specific header manipulation technique?
Take a look at at the digest authentication realm configuration.
The 403 usually stems from a mismatch between the expected dynamic realm and what the registrar sends.
Verify the realm string in the trunk settings matches the WWW-Authenticate header exactly.