Help for a iphone newbie

[phonehome]

Just bought a craigslist iphone in an effort to join the technology age.
Specs: iPhone 3gs, 5.0, BB = 05.16.05
In order to use my tmobile sim, i understand i need to first jailbreak, then unlock. After reading, it seems that this combo of OS and BB might make this difficult. I have read some that in order to unlock, i need to downgrade or upgrade the BB, however this may affect the GPS functioning of the phone. Is there a way to jailbreak/unlock from these current settings? I would love to keep the GPS. Thanks so much.

 

[Jmills87]

The 05.16.05 baseband is not unlockable so your only choice for unlocking would be to install the iPad baseband on your phone which permanently voids your warranty and 9/10 will cause you to lose GPS capabilities. However, this is the only way for you to unlock so it's either that or get a different iPhone with an unlockable baseband.