provided by Star2Billing S.L.

Hello
From the begining of our asterisk 1.4.41 and a2billing 1.9.3 installation we are suffering with an issue.
From time to time sip calls are hanging up at 20 seconds. The interesting point that this problem does occur from time to timea and when this happens it affects all my sip clients. i know that it is not related with a2billing


I spent several hour in searching the reason in web but couldnt find a solution. There are several things written in forum but no change for me.

My asterisk server is not benhind firewall and Nat. this problem occured from time to time for connections that are behind and also for connections that are not behind nat

i found these in asterisk logs
Maximum retries exceeded on transmission NWNmOTk4N2FlZmE1YjU5NDdkM2M5MGNjMTFhNmU1NTY. for seqno 2 (Critical Response) -- See doc/sip-retransmit.txt.
and the next sentence is

Hanging up call NWNmOTk4N2FlZmE1YjU5NDdkM2M5MGNjMTFhNmU1NTY. - no reply to our critical packet (see doc/sip-retransmit.txt).

Today i was on my pc and able to execute " sip set debug on " in asterisk cli and got the debug file

Looking forward to hearing a solution for this problem


Yours
Rock

This is related to firewall issues in addition to the "nat" and "canreinvite" settings.

Set "canreinvite = yes" ("directmedia = yes" ;Asterisk 1-8) in the general section of sip conf. nat = yes for sip peers, host=dynamic. Check fire wall logs.