Here’s another interesting phone-over-Internet approach that also works over existing telephone lines: the PhoneGnome.
This is how it works: A user connects the PhoneGnome via an ethernet cable to his of her home network, and to a PSTN wall jack using a standard telephone cable. When the PhoneGnome powers up, it automatically reports in to a server to let it know it’s online and what its PSTN phone number is. That’s the entire scope of the basic installation.
Once installed, when the user dials a telephone number, it checks with the server to see if that number belongs to a registered PhoneGnome user. If it does, the call is made directly via the IP network, bypassing all PSTN toll charges.
The PhoneGnome also works with non-PhoneGnome accounts like BroadVoice, VoicePulse Connect. In a nutshell, the service seems to straddle the best of old-style telephony and the best of the new — including the public SIP protocol.
I’m not clear whether the PhoneGnome works overseas; I see no reason why it couldn’t.