iPhone Unlocked successfully but after a while "NO SERVICE"

Hey,
I just unlocked my iPhone using anySim , everything was right I even recieved calls and sms but after a while I get "No Service" , when I search for networks on career setting it find the network but I get the ("Your network is no longer available..." Dismiss / setting ) msg when i try to connect to it?!
I also realized that every time i unload the commCenter and load it again it works but just for 10 , 15 mins and no service again...anyone know what can I do to make it work permanently :( :confused:

try doing a restore on ur iphone, this won't take off the unlock, you'll just need to jailbreak and reactivate your iphone.
hopefull that will solve the problem.

I think there's something wrong with my network ...It works great with prepaid sim cards:confused: