I am not trying to be a party pooper cause this might work for someone but I do work in IT professionally and specialize in communications, networking and security so I feel the least I can do is share a little info.
The company that provides this service is called Ring Plus and they are owned by Straight Talk who is themselves owned by Wal-Mart. I have unlocked about 15 of their phones for clients of mine who brought them in as "fried" or unable to call etc. to my company (ES-Tech) now as far as the basic service it is okay and cheap but the amount of hidden code, junk files, malware and spyware is huge not to mention the trojan that forces a ton of adds onto the outgoing call that you have to listen to when placing calls. I think they can even play the ads when people call you.