[asterisk-users] PJSIP configuration question

Joshua Colp jcolp at digium.com
Tue Dec 16 10:11:56 CST 2014

Dan Cropp wrote:
> I corrected my local_net setting (based on advice from network admin).
> I have tried several different values for the from_user and still have
> the same problem.
> Asterisk receives the OK from Vitelity.
> Asterisk sends the ACK (without a Contact header).

A Contact header is not required to be in the ACK.

> Vitelity doesn’t seem to process it, so they send an OK again.

I'd try to isolate this further as there's two possible things:

1. The ACK never got to them
2. They didn't process it

> The OK receive, Transmit ACK occurs 4 times.
> A short while later, Vitelity hangs up on my cell phone.
> Asterisk is never told the call  is gone.
> If I hangup the call from Asterisk side,
> Asterisk sends the BYE message.
> Vitelity responds with a “SIP/2.0 481 Call leg/transaction does not exist”
> Again, the trace indicates the ACK message is missing the Contact header.
> Additional note: the network admin is asking why the local_net,
> external_media_address, and external_signalling_address are needed.  He
> wrote me…“You should NOT have to know your public IP. The firewall
> should be doing fixup commands to change the values in the packet”

This can cause major problems. I've rarely (if ever) come across an ALG 
(that's what that is) that didn't break something.


Joshua Colp
Digium, Inc. | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org

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