So I've got a jailbroken iPhone4 on FW 5.1.1 and BB 1.59.00. I've got a T-Mobile sim working in it as well. The phone meter shows only one bar at all times. I have heard that this is a bug and that its purely cosmetic. I would be ok if that was the only issue. My signal comes and goes even in prime T-Mobile signal areas. My phone will jump back and forth from one bar service to no signal repeatedly throughout the day. When it says "no service" it really means no service. It always comes back a minute later though. I took my T-Mobile sim out and tried it in a first gen iPad and it works great with full bars and no service interruption at all. I am thinking that the antenna or some other internal component is faulty. I've taken apart other iPhone 4 devices and replaced screens and digitizers. I've never taken this one apart and neither has anyone else. I was wondering if anyone had any suggestions on why this might be happening or which part I might try replacing and where that part is located inside the phone. An ATT sim in this phone will also show only one bar and sluggish/intermittent service. Any help would be greatly appreciated.