Is my iphone blocked or something?

I bought a iphone 5 from the carphone warehouse its on 3 network PAYG anyway i have no service its been that was for a few hours i put a 2 different sim cards in and both times the network name came up but both signals were flat:/ ? Any ideas anyone? Lol i checked my iphone status and said it was activated thats all i have atm

Added (1). I get amazing signal with 3:( and my boyfriend is also with 3 and has the iphone 4s an his is full i'm using it right now lol

Added (2). I have had the phone since june on 3 network (phone is unlocked) and its randomally started doing it today

Try walking down the road a bit - probably no signal (3 are useless!) If I walk from the front to the back of the house, I lose all signal.

The first 3 hours there's no service since you have just bought a new phone. I got a new iPhone 5 and it had no service so almost 4 hours. Then I saw the bars come back on it. It takes time for the iPhone to connect to the service

It probably is locked to another network

Put the phone in the microwave for about 7 seconds (it heats up the signal finder in your phone and looks very fast for signal) If that doesn't work get the new blackberry z10

Your iPhone isn't blocked. The problem is with your network provider so you should go to the nearest carrier shop and check with them. My father had a similar problem before.
Regards,
Amr El Akkari