Unlocked iPhone 3GS 4.3.5 Firmware - Invalid SIM/SIM Failure

[xsuper7x]

Just as the title says, I used redsn0w to jailbreak and unlock my iPhone 3GS (Baseband 5.16.02), added the redsn0w source in Cydia, installed it, restarted my springboard... Then when I insert my T-Mobile SIM card I get "Invalid SIM" and sometimes "SIM Failure"... It shows 1 bar of service with no text next to it and when I try to make calls or send messages they fail.

PLEASE HELP

I've been trying to get this iPhone working with my SIM card for the longest time...

 

[Gregoris]

Before you can follow these instructions you must have a jailbroken iPhone and you must be on the 04.26.08, 05.11.07, 05.12.01, 05.13.04, 06.15.00, or 01.59 baseband(modem firmware).

 

[xsuper7x]

Stupid me. /facepalm

I went back and found that I must have overlooked the step where it said the specific basebands the unlock worked for, (mine being 5.16.02), so after hours of headache trying to downgrade my iOS to 4.1 and getting tons of error codes from iTunes while trying to restore, I was able to upgrade my baseband to 6.15.00 and am restoring to 4.3.5 as I type this to jailbreak and unlock.

I am 99.99% certain that the unlock will work for me this time. So yeah...