[asterisk-users] Ring back problem on SIP calls. Order of 183 Session Progress and 180 Ringing

[Chris Abel]

Hello everyone!

I've had this problem for a while and cant figure it out. When an outside
caller calls an extension on my asterisk system, they do not hear any sort
of ringing. Inside extensions calling other extensions do hear ringing. We
have 3 other asterisk systems that are configured the same way, but do not
have this problem. We think it has something to do with asterisk 1.6. The
other asterisk systems are using 1.4. I have played around with
"progressinband" in sip.conf with now success. Whatever I set
progressinband to, it doesn't seem to change a thing. "183 Session
Progress" never seems to be called when looking at sip debug. It is only
when I use the Progress application before my dial command that I get the
"183 Session Progress" message in sip debug.

We also have a Trixbox system using asterisk 1.6 that had the same
problem. The way I fixed that was to set progressinband=yes in sip.conf.
This did not work with this system (Yes I know Trixbox is completely
different).

The only thing that looks different is the order in which "183 Session
Progress" and "180 Ringing" get sent in sip debug. On the troubled
Asterisk system 183 gets sent before 180. On the fixed Trixbox system 180
gets sent before 183. Does this mean anything? We also have Polycom Phones
which I heard are notorious with ringback issues.

Thanks,
Chris