Phone shows service>Cant Call/Receive>Hard Reset>Recovery Mode>Works then doesnt

[iph0n3]

Back once again
Heres the phone info
Model#: A1241 MB490DN
Size: 8GB
Software Version: 3.1.3(7E18)
Modem Firmware: 05.12.01
The Problem: The iPhone listed above will show a network and have full service but then cutout after about 15 minutes while it has full service. The problem will then escalate and the phone will no longer work while showing full service. The phone will only work for about 15 minutes after it has been hard reset and then synced with itune after being sent into recovery mode. THE PHONE HAS NEVER BEEN JAILBROKE OR UNLOCKED. I am trying to fix this for a friend but have to no avail failed miserably. If more info is needed please ask so I can get this troublesome device outta my sight.

Thanks

[Robcoffee]

If it shows full service bars but gives call failed when trying to make calls and can not send texts it sounds like it is imei blocked because it has been reported lost or stolen - the short period it works for most likely is caused by a delay in the network picking up the imei.

[iph0n3]

Are there any other reasons beside the above listed reason? Because I took him to buy the phone.