Downgrading firmware and baseband on 3G 3.0

[rmk127]

ok i have a black iPhone 16gb

i installed 3.0 firmware
jb with redsn0w, everything went perfect
unlock by adding source in cydia, repo666.ultrasn0w.com with 3G turned off
and installed ultrasn0w

inserted my SIM card and everything worked great..

for 2 hours


after that, my signal bars became unstable

i also had fake signal, which means that i have bars
but i cant make call, nor send or receive text messages
but i STILL have signal bars on the top

so now, its just one of those on and off phones
i put my SIM in my motorola phone and i great great signal and never lose a bar

but as soon as it enters the Jailbroken and Unlocked iPhone,
my signal becomes unstable
i get everything from full signal to no bars to no service to no sim installed






so i was wondering if anyone can post steps to
-downgrade to 2.2
-downgrade to 2.28 baseband

[iPhoenix3g]

Are you on t-mobile UK or US?

[rmk127]

US