[OpenSIPS-Users] ACK for invite with wrong Cseq

[Schneur Rosenberg]

Hi, I'm using OpenSIPS 2.2.2 and I'm using create_dialog with the "Pp"
options, most calls run fine, but I have got complaints about calls
getting disconnected after about 30 seconds, I ran a trace and I
realized that OpenSIPS sent a INVITE with CSeq 601, the called party
picked up after approx 34 seconds and sent a OK with CSeq 601 which
the gateway (Freeswitch in this instance) forwarded to OpenSIPS, but
before OpenSIPS responded with a ACK it sent a ping Options to the
gateway with CSeq 602 and the gateway replied with a OK, and then
OpenSIPS sent the ACK for the INVITE  but used the CSeq of the Options
602 and not from the INVITE,601, therefore the gateway kept on sending
OK's with CSeq 601 which OpenSIPS responded every time with the ACK
but again with the CSeq 602. then after approx 30 seconds the gateway
sent a bye with Reason: SIP;cause=408;text="ACK Timeout"