I have opened an account for my relatives with freecall.com few months back. They offer free calls to US and many other countries, assuming you have loaded some credit in their account. (Free calls worked few days even without crediting the account.) The incoming number problem I solved with IPKall. For outgoing calls the caller ID shows a random number, which is a bit of annoyance.

To open an account you need to download their softphone app first. After that you can put the credential to a SIP adapter (Grandstream HT486 in my case).

For comparison shopping I found this web site handy:
http://backsla.sh/betamax