Hi Guys, I'm after a bit of advice.
I currently have an iPhone 3GS on 4.2.1 with Baseband 06.15.00.
I can unlock the phone no problem and get a full signal with T-Mobile UK but cannot make or receive calls or send or receive texts. When I try to make a call, it comes up "Call Ended". 3G does not work either. I did have service for a short time, but it crapped out on me.
The phone was jailbroken with Snowbreeze and because of the baseband I cannot restore to stock firmware to start again.
I have tried switching 3G off and on again, booting tethered and rebooting the phone with redsn0w.
I'm at the end of my tether (no pun intended) and am looking for a straight answer.
What else can I do to restore signal to this phone?

Any ideas?