No on my LG U8130... Is it blocked?

My girlfriend came back from the market with a nice LG U8130 mobile phone (no box, charger etc), knowing I needed another as I had dropped mine..

There was no life in the phone so I went and bought a charger..after a quick charge and the insertion of a new 3 SIM card, the phone sprang to life, allowing me into all menus etc..

The only problem now is that, it doesnt matter where I go, I cant get a signal.. the signal bars are no existant...

I was wondering why.... Is it blocked... If so how do I unblock it...