iphone 3g showing no signal bars but shows carrier name

[steve99750c]

hi guys

recently jailbroke iphone 3g on 4.2.1 ios and also installed ipad baseband using redsn0w
however after the unlocking process is done using ultrasn0w i dont get any signal bars on the phone but i can see the carrier name
ive tried o2,vodafone,orange simcards and still the same no signal bars but can see the carrier name,however when i put a tmobile sim card in
i get full bars of signal and the carrier name but cannot dial or send texts etc,ive uninstalled the ultrasn0w source and reinstalled and still the same,please help