I just wanted to let you know about the provider I use, which is Axvoice (
http://axvoice.com/ ). I have their unlimited $18.99 plan for the United States and Canada. You can use your own adapter. You get two phone numbers in the United States and/or Canada. I have one in BC and another in ON. I also use the free service IPKall (
http://www.ipkall.com/ ) and have another number in WA.
The best thing about Axvoice so far is their service. They answer their support phone calls and emails very fast. This is my third VoIP provider because of service issues and so far they are the best. Avoid Vonage and Voipia Networks at all costs.
On another note, I used the Voxilla wizard online to configure my Axvoice account.