What it means
No final response arrived in time. The request was sent but nothing answered before the timer expired. This usually points at a broken path rather than a busy user.
SIP/2.0 408 Request Timeout
Common causes
- The destination is unreachable or down
- A firewall is silently dropping the packets
- Lost UDP packets on the way, with no retransmission getting through
- One-way signalling because of NAT, so replies never return
- The wrong port or transport for the far end
How to fix it
- Confirm the destination is reachable and listening
- Check firewalls between you and the far end
- Verify the transport and port, and try TCP if UDP is being lost
- Inspect your Via and Contact for NAT problems that stop replies returning
- Use an OPTIONS ping to test the path independently of a real call
See it in your own trace
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