o2 x1 query

[parasite]

I got an o2 X1 off someone I dont know.

When I put my o2 SIM Card in, it accepts it, reads everything and registers as normal, but when i try and do anything (call/sms/gprs) it says "Network busy". I cant recive incoming calls either.

But when I put my Orange SIM Card in, it registers perfectly, and everything works as if id just bought it.

Has th phone been blacklisted? or is my SIM just a twat

[GSM Super Star]

Sounds Like ya sim Mate