This is another great benefit of going with a true VOIP solution like VoIP.ms; I've made calls over Gogo inflight wireless, and pretty much anywhere you can get onto Wi-Fi internationally saves you a TON of money.

Lots of flexibility, and you can start doing cool stuff with IVR's (I have a recording for anonymous callers that get dumped directly to voicemail unless they press 1, which gets rid of most robo-dialers for instance), iNum (my wife was able to make a free call from her hotel in Canada to the local iNum access number and get forwarded to our home phone, all free), callbacks, etc.

Amazingly cheap too, I bet most here would end up paying less than $10/month to replace their home landline.