For over a year and half, I was using Magicjack as a service with my Asterisk server and I have helped some people to setup their Magicjack to work with ATAs. Last month, Magicjack had a firmware upgrade and they started random rotating password which caused the ATA method stopped working. If anyone come cross a new patch or method, please contact me.
The backup method to have a free or low cost phone service is to use Whisle Phone with ATA. Whistle Phone provides a free local DID number (some major cities at least) and free calls to the United States. The draw back of Whitle Phone is that you will have to listen to a short ad everytime you call out. This can be fixed if you load money into your account. If you live a place where Whistle Phone does not provide a local number, you can always use Google Voice along so you will have a local number.
Talking about Google Voice, I have used the service even before Google stepped in. Back in the old days, the service was calls Grand Central. Google Voice is already out of beta which means everyone can use it. You DO need an US IP address to sigh up. You can use it with ATA but you will need some other services along. You can use your sipsorcery and IPKALL or Sipgate free DID numbers to register under sipsorcery and put a simpel dial plan for dialing out via Google Voice. The newest method of using Google Voice is to build your own PBX in a flash which the latest version supports Google Voice out of box. You just need to put your GV information as well as your sipgate or IPKall info. You can find more info here http://nerdvittles.com/
I hope this infomation will helpful to some people.