You don't need to disable SIP ALG with the newer U-verse firmware. I think that option moved to a device specific firewall setting - one of the application choices is "SIP gateway". I do NOT use that option and it works fine, when it definitely did NOT work with SIP ALG enabled on the earlier U-verse firmware.

I just switched to Voipo. All I had to do was plug in the Grandstream adapter and it seems to work with my U-verse connection. With my previous provider (that used the same TA) I had to forward a few ports before I could make a call.