Why only Canada? Seems to be Facebook is copying bbm voice.
I was expecting that response. If it was flagged as "US-only", which is very common for such services in beta, I betcha nobody in the US would think twice.
It's probably limited to Canada due to a smaller test market. Canada has just as mature, but smaller, market as the US, so it's a good testing ground. And maybe there's a Canadian company assisting Facebook with the implementation. (but not RIM, haha)
----------
Wow, I can't even imagine how much processing power and bandwidth that would be required at the Facebook data centers to handle a billion voice calls, if this would roll out worldwide some day.
----------
It's possible it's intentional to reduce coverage while they're trialling the service and infrastructure. A scaling / stress test perhaps?
Skype uses a peer-to-peer system, and I expect Facebook will too. Only Apple chooses to channel everything through their own servers, but not sure if that has changed with iMessage and FaceTime.