said by djrobx :

Thanks, but with AT&T U-verse, it's impossible to put anything "in front" of the AT&T's modem - it's a built in modem/router combo. I can't use DMZ, because I am running my own DHCP server for a few different reasons. AT&T's RG gives you no way to set a DMZ host if it's not serving DHCP.

I did read your link with the WRT54G instructions, but if you follow it to the end, PhonePower gives you some ports to forward, but then proceeds to instruct you to still put the PhonePower device into the DMZ!

I can treat the U-verse hardware as a "dumb" modem, but then I will have to ditch its built in wireless functionality. I have too many devices in my central closet at it is, I don't really want to add yet another router or wifi access point.

Its been fine all weekend without DMZ, so hopefully it'll be OK!