Is it possible to jailbreak an iPhone 4 for tmobile?

[babytigger88]

I wanna sell my iPhone 4 at the end of the month when I am eligible for upgrade to the iPhone 4S. One of my friends is considering buying my 4 off me but he has tmobile. Is there a way he can jailbreak it to use it with tmobile? If so how could he go about doing it?

 

[jeffrey1027]

Jailbreak and use ultrasn0w if you have a compatible baseband

 

[babytigger88]

I can explain to people about the phone a d show them things but when it comes to getting technical like that I have no idea what that is lol would it work with the iOS 5 update?

 

[BarronN30]

You would have to jailbreak it and unlock it, and like jeffrey101 mentioned, you need a compatible baseband.
I don't think it will work for the iOS 5 currently because there's no jailbreak for that yet.
When I jailbroke my 3GS, I noticed the unlocking/jailbreaking was different than iPhone 4 (easier than 3GS). So hopefully someone else can fill you in with more details.
But right now, check what iOS you have now and the baseband and use this to see what process you can use:
google iclarified jailbreak wizard (I have below 10 posts right now so I can't post the link)

 

[Stromie]

pardon my ignorance, how does one gets a "compatible baseband"? Who has this information?

 

[Alli]

I've moved this thread to the jailbreak forum. You'll get your answers here, or you could look around where they've already been answered.

 

[anon(5335877)]

pardon my ignorance, how does one gets a "compatible baseband"? Who has this information?

You either have it or you don't. Usually when you update your firmware, you get a new baseband. If you updated recently you most likely do not have a compatible baseband.

If nothing has changed, you find it in the Settings > General > About > Modem Firmware. For the iPhone 4, the only unlockable baseband for ultrasn0w is 1.59.00.

If you have an unlockable baseband, and you want to upgrade your firmware but keep your unlock, you must preserve your baseband.