Got a pay as you go 3G today secondhand, tried to activate it with a pay as you go o2 sim but activation didn't come through before I decided to jailbreak it and unlock it. Now o2 sim comes up saying "phone not allowed" and t-mobile sim shows full service but can't make or recieve calls. When I try calling it a message saying that the number is not receiving calls comes on.

Have I done something wrong or is the phone wrong in some way.

I'd be really gratefull for some help on this !