Oh, Russell, another thing:

What brand(s) of ATA do you use? Any preference for brand of ATA? Grandstream vs. Linksys vs. whose else does Voipo supply? Or for the end user, it's all the same?

Are these in front of the computers at your location? (and I guess you are using the NAT of at least 1 of the ATAs for that?) or are the PCs and the ATAs in the same subnet / all connected to the same router?

Thanks!