We have an IP7000 running off of an IPedge that works perfectly while connected to the same local LAN. When the Polycom is reconfigured to work offsite, the phone will not stay registered. I can get it to register and make a call, however the call will drop in usually under a minute and the station will un-register from the edge. Even when idle, the station will un-register after so long. It is a Ubiquiti firewall and Comcast as the ISP. The firewall is pretty much swiss cheese at this point. Any ideas?

We may have narrowed this down to the Comcast modem thanks to this doc here, which was found on a post on the Installers board. The modem is the DPC3939B which has SIP ALG enabled and cannot be disabled. When this modem was initially installed we were told by Comcast that it could not be bridged. In doing some more digging, we think a newer firmware has come out for this modem that makes bridge mode possible. We are gonna try that tonight and see if that makes a difference before requesting a different modem.

Good luck,

I remember having a bunch of problems getting an IP4100 SIP phone working over the Internet to a CIX.

SIP ALG was intended to help a SIP call, yet often this needs to be disabled to allow SIP to work correctly. It's a bit surprising that they won't let you turn this off. It reminds me a bit of SPI firewalls and the problem with the Toshiba IPT. If a customer had a Linksys WRT router, I basically told them to get a new router.