I had this problem this past Monday when I woke up in the am my phone was locked up on a incomming call as it sometimes does, I pulled the battery to reset it as usually but then it came up with "Network Search... T" <-- (Red T)

it never connected no matter how many times it reset it, I took the phone to sprint who then told me they were ordering me a new one, but I would have to wait 3-5 days! I couldn't be without a phone this long so I tried searching the forums, but found nothing relating to the issue, I then took the battery out and noticed that the radio might be located directly behind the battery, I firmly massaged the complete area for about 15 secs, put the battery back it and Bam! it worked!

I'm still have a problem though where I have signal but don't get incomming calls, my phone never rings, but if I make on outoging call such as VM then I'm able to get incomming calls...very strange, I think it might be related to sprint though since after Rita came though Houston...

Anyway hope this helps someone else out