Iphone 3g I believe its unlocked but not jailbroken?

ok heres the deal I got a great deal on a Iphone on craigslist I went to have it jailbroken and unlocked and also purchased a plan through tmobile.(separately) but its not working. I have been told that my phone is unlocked but not jailbroken. I went to the settings application hit general and then about. the songs that were on the phone are gone (I bought the phone used, and the previous owner had put about 50 songs on the phone) also under network it says not available, the capacity is 7.1 gb version 2.2.1 carrier still says at&t 2.9 can anyone help? can this thing be unlocked or do I just have a really expensive paperweight? I talked to the person that tried to unlock/jailbreak the phone and he said first the snow app was unavailable I went home and checked the internet and found the yellowsnow app. so I texted him and now hes saying it takes 24-48hrs to take effect.
Help!!