Investigating reports of failed SIP Transfer calls in US East

We have identified the root cause of both spikes and have ensured safeguards to prevent a recurrence. We've been monitoring since 18:05 UTC and have seen no further transfer failures, and have confirmed that SIP transfers are operating normally. We will follow up with a detailed post-mortem.

No transfer failures has been observed since 18:05 UTC and SIP transfers are currently completing normally. Impact was limited to a small percentage of calls between 15:48-16:08 UTC and 17:24-18:05 UTC. We're actively monitoring while we investigate the cause and put safeguards in place to prevent a recurrence.

We're investigating an elevated rate of failures when transferring active SIP calls in the US East region. SIP calls themselves remain connected, and inbound and outbound calling are otherwise operating normally.