Maximum retries exceeded on transmission

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[edit] SIP implementation bug on device

This is not a problem with Asterisk - essentially what happens when you cancel a call is this:

1. Phone sends CANCEL
2. Asterisk sends 487 Request Terminated
3. Asterisk sends 200 OK
4. Phone sends ACK to acknowledge the above messages.

Your phone/device is not sending an ACK back, so Asterisk continues to send the 487 Request Terminated because it knows no better.

This is a problem with SIP non-compliance by the phone/device, specifically, rfc3261, section 17.1.1 requries an ACK to the 487. If Asterisk do not get ACK'd, it should resend.


If you are using some softphone - try to change it.

If you are using some hard-phone - try to upgrade/downgrade firmware.

[edit] Asterisk under NAT

In CLI also visible: No reply to our critical packet

WARNING[25126]: chan_sip.c:2057 retrans_pkt: Maximum retries exceeded on transmission for seqno 102 (Critical Response) -- See doc/sip-retransmit.txt.                               
[2011-08-10 09:45:16] WARNING[25126]: chan_sip.c:2079 retrans_pkt: Hanging up call - no reply to our critical packet (see doc/sip-retransmit.txt).    

It is possible that Asterisk is under NAT and not properly configured.

Solution: Asterisk under NAT

If it does not help - change your router.

[edit] Other network problems

Proceed with: sip-retransmit.txt

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