Help with my iPhone 3G-S

[swat16]

First off, I am a novice when it comes to this stuff. I want to unlock my iPhone 3G-S so I can switch to T-Mobile because I get no AT&T service at my house. I downloaded blackra1n and jailbroke my phone. My iPhone says "Version: 3.1" and "Modem Firmware: 05.11.07" Can this phone be unlocked? Second, I also downloaded Cydia and then added Source "ultrasn0w." Now, my phone will not work on AT&T. I called Apple and they can't help me so I'm hopnig someone has an idea of what I did wrong. Help!

UPDATE: I uninstalled ultrasn0w and now my phone works again. But back to my other question. Can anyone tell if my phone can be unlocked? If I had inserted a T-Mobile sim card while my phone was not working would it have picked up on T-Mobile's network?

[bmw7777]

No it cannot be unlocked. Ultrasn0w was made to unlock lower firmwares and basebands. It will not work with the new baseband 05.11.07, that's why your phone stopped working. You are stuck with ATT. You cannot change to TMobile unless a new unlock comes out or a piggyback SIM is released. I don't know when and if this will happen. Also just a hint. NEVER NEVER tell Apple that you jailbroke your device, they will refuse any assistance because they are dicks.

[CaptainChaos]

Maybe you could look into AT&T's microcells so that you can get service at your house.

If you knew someone else with AT&T Maybe they would trade you phones if they were still on the lower baseband.