I thought it may be then antenna unit so I replaced it for a new one but still no service. Its an iPhone 3G 4.2.1 05.13. I dont understand what can be the issue. I tried resetting network settings, resetting all settings. Restored with original firmware and jailbroke with redsn0w. Cant figure it out.. at this point my head is spinning and cant clearly think of anything else. Am I missing something?

Is this a UK locked phone? It's possible it's IMEI blacklisted, but I don't really have much information to go by from the post.

It's possible it could be the comms board or the antenna cable, but if you've replaced the cable and are 100% certain sure it's good, then it very much could be a bad comms board. When did it start happening?

Dude, thank you for throwing some help man, I really appreciate it. I dont know where the phone came from, I just couldnt figure it out so I went ahead and sold it.
I know the antenna was good cause I tried 2 brand new units. I even installed the iPad baseband at the end to see if that would help but still nothing.
Anyways, what is a comms board?

Comms board is thhe sub-part in the iPhone assembly that holds the baseband chip and (if I recall correctly) the wifi and bluetooth chips as well. It connects to the main logic board via a fairly tight connector. It's possible that the connection to the logic board was broken, thus stopping it from responding to any requests. Alternately, there have been reported cases of corruption during baseband flashing that can brick the device and would require an actual chip programmer to re-program.

You can see a pic of this here: http://i.cmpnet.com/techonline/uth/p...oardtopBIG.jpg

Oh wow.. thats something Im not attempting to repair lol, dont have the tools nor knowledge to do it. So that little thing that may have been the issue, is located under the aluminum pieces that cover most of the board? Because if it is, I dont see how it could've been damaged.

Originally Posted by LS6_5SPD

Oh wow.. thats something Im not attempting to repair lol, dont have the tools nor knowledge to do it. So that little thing that may have been the issue, is located under the aluminum pieces that cover most of the board? Because if it is, I dont see how it could've been damaged.

Problem with comms board issues is that they are hard to diagnose. It could be caused by something simple (yet darn near impossible to fix) like someone unplugging halfway through a baseband update, or it could have been something mechanical like the cable being loose when the phone was removed and put back together. Even just taking the phone apart will stress specific connections, so it's always worthwhile when re-assembling to check the crossed t's and dotted i's to make sure. I've seen (many more than once) people replacing dock connectors, etc., only to find out that they've accidentally unhooked antenna or the comms board, etc. Definitely a lot of small pieces in a very small case, very easy to accidentally pop one of the connectors out.

If you look at the picture, you'll see the connector on the bottom right. As I recall, on this model phone, it's nothing more than a tension clasp -- the connector seats into a mated female connector and is held in only by the tension of the connection and the pressure from the front and back cases / digitizer / glass, so it's very easy to warp the board while jiggling things loose and have it pop out, or only make good connection on half, etc.

In any case, probably doesn't matter since you hocked the device, but if it ever happens again....

Yea man I got rid of it n let somebody else deal with that. But thanks for all the info buddy! I'll recall it if this situation comes up again.

Oook.. here we go again. This time is a 3gs. I replaced the lower mic-speaker unit (where the antenna is if Im not mistaken) and now it goes into searching and then to no service.

you said :
If you look at the picture, you'll see the connector on the bottom right. As I recall, on this model phone, it's nothing more than a tension clasp -- the connector seats into a mated female connector and is held in only by the tension of the connection and the pressure from the front and back cases / digitizer / glass, so it's very easy to warp the board while jiggling things loose and have it pop out, or only make good connection on half, etc.

I cant see it lol. I will try another unit to make sure its not the antenna (which hopefully is)

nevermind!!