For conversation purpose, I’m referring to SIP as the use of callcentric.com with a Linksy SPA1001 ATA. That being said, I noticed when calling between ATAs (that are both using callcentric.com) the call quality is superior, so I am venturing that the voice packets are sent directly from one IP address to another, with the least number of hops possible.
I have no way of verifying this with data: if you do, please share. If my hypothesis is wrong, please advise why.
The reason that I am interested is because I am standing up several ATAs overseas. If inter-ATA calling (all using callcentric) is truly Point to Point, then I can set the expectations among users that calls will be of the good quality.