Downgrading Baseband from 05.16.02 to 05.15.00

My ultimate goal is to use this iphone w/ T-Mobile. The version is 4.3.5 and the baseband currently is 05.16.02. After doing research I understand that I need to have 05.15.00 as my baseband. HOW DO I DO THAT?

I have already jailbroken the phone but every time I select the ipad baseband (05.15.00) it brings me to the itunes screen on my phone.

I understand the risks by updating the baseband to 05.15.00.

Thanks in advance for your help!

I'm not sure you can change the baseband on your iPhone, jail broken or not. While you can certainly use the iPhone with T-Mobile with the proper sim card, it will never be able to go 3G. It will be limited to EDGE only. Next model (iPhone 5) may be different and also since T-Mobile has been bought by AT&T all that might change.

Im pretty sure you have to use ipads baseband 6.15.0 im currently working on downgrading to that bb with a jailbroken 3gs that was jailbroke with jailbreakme.com ive heard a little about fuzzyband in cydia but havent been able to get it to work yet anyone have any suggestion other then redsnow it cant seem to find my ispw and when i tried to create one with pawnage tool it wouldnt recognize it and itunes wouldnt let me restore to it? any suggestions?