This incident has been resolved. We will follow up with a detailed postmortem as soon as possible.

An upstream carrier reverted a codec change that was causing one-way audio issues on calls to LiveKit-issued phone numbers. As of 21:10 UTC calls are connecting normally and we are no longer seeing the issue. The upstream codec change has impacted calls from T-Mobile and AT&T carriers. No other SIP providers were affected. We are monitoring before marking this resolved.

We are investigating elevated issues in calls connected to LiveKit Phone numbers where callee audio is not being heard by the caller. This is currently only experienced for numbers issues by LiveKit, and no other SIP provider connectivity should be affected. Our team is actively investigating this.