SIP 487 Request Terminated & 408 Request Timeout in Teams Direct Routing: NAT Timeouts, Carrier Ring Timers, and Firewall Deep-Dive
When analyzing VoIP traces in an enterprise Microsoft Teams Direct Routing deployment, two SIP response codes frequently cause confusion among voice engineers: SIP 487 Request Terminated and SIP 408 Request Timeout. While a SIP 487 is often completely benign—representing normal call abandonment by the calling party or an unanswered call forwarding to voicemail—it can also…
