The root cause was an incompatibility in how ElevenLabs handled mid-dialog re-INVITEs. When SIP providers sent re-INVITEs, ElevenLabs responded with 488, which some providers treat as fatal, issue a BYE, and terminate the call. Per RFC 3261, a 488 should not necessarily result in session termination, but provider behaviour varied.
Resolved
The root cause was an incompatibility in how ElevenLabs handled mid-dialog re-INVITEs. When SIP providers sent re-INVITEs, ElevenLabs responded with 488, which some providers treat as fatal, issue a BYE, and terminate the call. Per RFC 3261, a 488 should not necessarily result in session termination, but provider behaviour varied.
Monitoring
We have pushed an update, and we are currently monitoring the situation.
Investigating
We are currently investigating an issue with SIP calls that is impacting the transfer-to-human flow. We are working on a fix.
