Call drops

I have been chasing a problem with aastra phones and asterisk v 1.4.0 and 1.2.15 as well. You will start the call and it will connect, then i will get a warning message on the console stating that the system exceeded the maximum retries for a packet to the phone and the call will drop.

this is the message:
Feb 26 19:32:42 WARNING[24976]: chan_sip.c:1226 retrans_pkt: Maximum retries exceeded on transmission 276bc0ff526178ba52c2cf72845b20d6@ for seqno 1845472325 (Critical Response)
Feb 26 19:32:42 WARNING[24976]: chan_sip.c:1243 retrans_pkt: Hanging up call 276bc0ff526178ba52c2cf72845b20d6@ - no reply to our critical packet.

same message every single time this happens.

What firmware version have you got on your phones and what is your NAT situation?

Sounds like NAT for firmware version on all the aastra phones. After reading your reply i check the nat settings on the phone and on a whim turned on teh nortel nat setting and everything is working fine now.

I hadnt really thought about nat as we are behind a netgear and the server is in the dmz. Of course that a whole other story.

try the latest firmware also try playing with the params SIP NAT PORT and SIP NAT IP…