Not sure how many other people have experienced this, but my iPhone randomly will crash and completely lose its radio abilities, it's happened about five times and even on stock firmware. No IMEI, ICCID, or even a SIM card is detected and it just searches for a signal. It boots to a connect to iTunes screen that says there is a problem and to restore the phone, you cant even access the springboard. When I restore it gives me Error 23, which is apparently a hardware error. Most people consider the phone bricked at this point.
I figured out how to fix it before, but it's annoying. I have to take the back off, remove the battery connector, then plug it back in and immediately put it in DFU mode and restore in iTunes. This gives error 1013 instead of 23 and I can go from there, but it's a hassle considering this just happens randomly sometimes.
BUT, I have found a much better fix. I simply put the phone in DFU mode, and ran the fixrecovery app available from TinyUmbrella's site. It runs some code on the phone, then it boots back to where you were before with a working signal! It isn't the intended purpose of fixrecovery, but the error I'm getting must be a baseband chip issue that this fixes (temporarily). Sorry if this was posted before.