VoIP (VoiceWing) & Firewalls Help

[lyons at digitalvoodoo.org (Timothy M. Lyons)]

Has anyone out here successfully setup a VoIP TA (Specifically Verizon 
VoiceWing / Cisco ATA 186) behind
a firewall?  I'm having a lot of issues with connectivity from my internal 
segment and Verizons solution to open up
all UDP from the internet was not very helpful.

I got it limping along by placing the device in a secondary DMZ and punching 
some holes in the FW, but I'm still
not convinced it's correctly setup as it works fine when directly-connected to 
the net but had some minor glitches
on the DMZ.  As VZ had no more advice to offer, I'm reaching out.

--Tim