Random dropped calls lots of info

OK Im at my wits end here…

First my system
FreePBX 2.11
Asterisk 11.4
1 x Sipstation trunk (see details below)
1 x Sangoma PCIe card 4 port with three analog lines

I have the first outbound path the SIPSTATION trunk then the POST lines

what’s happening:
Calls will randomly drop after about 20 seconds. I see a number of posts with the “20 seconds” in there but nothing is fixing it. What I do see is something odd, when I watch the system and a call comes it I see two (2) channels being used. If another call comes in that number will jump to 10! Seems very odd as its only one more call.

I ran a tcpdump and while I have not captured a dropped call yet (its pretty random) I do see odd entries like “FROM: SIP# Protocol: SIP Packets 7 STATE: REJECTED” I have to idea why its rejected. The odd part is calls are working even when I see that. Again I have NO captured a dropped call.

Im using G.711 across the board, with GrandStream GPX1450 phones. Nothing special about the system pretty much out of the box with the normal settings.

I also saw the same issue with a different trunk provider so it seems to be either something on my end, or the configuration.

Any help would be MUCH appreciated, and my next move is to go direct to the Schmooze support but wanted to toss this out to try and get it sorted if possible!



That is very often caused by your firewall/pnat/router box not maintaining the state of the connection, many of these boxes “sip helper” ALG’s are badly broken.

Agreed… Im using a ZyWall USG 50 and there is a SIP ALG there, but it has been disabled. There are also tow other options Enable SIP Transformations and Enable Configure SIP Inactivity Timeout.

Nothing is checked…


Really sounds like your router is screwing with your SIP Packets. This is common with lots of routers trying to be smarter then they are. I suggest first getting a dumb down simple router.

Im going to put in a ticket with the firewall side of things, see if they can help sort out any issues.

Given that I have a Sipstation trunk, will they assist in getting this resolved?

Ill post what I find…