Hey sorry for the late reply, the iCommunity ipsw didn't work for me. As of right now it shows full signal but I know if I try to use it the signal will drop. Heres the info:

Version 4.0 (8A293)
Carrier 7.0
Model MB048LL
FW: 05.13.04

Right now its on the iCommunity ipsw with redsn0w and ultrasn0w unlock. I tried it with pwnage tool also and no luck, 3g off, cellular data on or off, no sim in tray... sim in tray and nothing I have tried has helped at all. The problem is in the unlock or the baseband, even with a forced downgrade to 3.1.2 it still did the same thing. I'm stuck and I hope there is a fix for it because it gets frustrating going back to a windows mobile phone

Just tried it, same thing except now I can't make calls. I get signal and it says tmobile then it starts to drop off, goes to searching then says no service. I downloaded 4.0 from the felixburns website since itunes will not let me download and save the os, it only lets me download and update

No, 1st iPhone would reboot during a call and keep going to white screen of death, it did it more when using the internet. New iPhone just loses signal, sometimes it allows me to make a call when it has full bars and sometimes not, I tried it with my girlfriends tmobile sim card and it didn't receive signal either. Tried my sim card in her unlocked iPhone with os 3.0 and it works fine. I don't think its the os because when I downgraded to 3.1.2 with baseband 5.13.04 it still acted the same way. It may be in the baseband or the unlock isn't working "all of the time"

Hi guys,
Any point in the right direction might help... here's what I got
Iphone 3g recently swapped from apple under warranty
iOS4
5.13.04 baseband
Tmobile sim
Have tried the pwnage 4.01 method with restore in dfu mode, somewhat successfully unlocked but it gets signal for a little bit and then drops it, goes from full bars down to searching then it says no service, out of nowhere it comes back.... maybe I can sneak in a call here or there before it drops it again. I disabled 3g before installing ultrasn0w, I have tried switching airplane mode on and off, reset network settings, downgraded to 3.1.2, retried 4.0 and it still keeps doing the same thing. I tried another tmobile sim card and it still does the same thing. It's extremely frustrating because I went from a phone that constantly shut off and would take hours to boot up to a phone that now I can barely use. So if anyone can help I would greatly appreciate it.
Thanks Guys

BTW I have access to a Mac and a PC