No Service after replacing battery on iPhone 3G

[mursel]

I would start with resetting the network settings. Next I would try calling your network and asking them to troubleshoot the issue by sending a signal to your device. After that I would get a new SIM card. If the problem persists I would consider the network and the areas in which you keep having the issue. There could be a dead spot or lack of signal in that area.

1. Network reset settings doesnt work!
2. Already called'em but didnt asked for sending a signal. I'll try that.
3. SIM replaced
4. My NOKIA N73 works perfect everywhere in my region with 3G our without.

Thank You!

[Dloc2]

This thread clears a few things up for me

Basically, if I am able to get wifi, that does not have much to do with the phone side of the antenna. I replaced a power button and the speaker assembly and also suddenly get No Service. That brass piece is sitting on my table disconnected from the board, could that be it?

Try this

How I recovered my iPhone's lost GSM signal!