BB Tour :: How To Change IMEI Code?

I'm on the o2 uk network, and have a BB Curve 9630 (I think lol, can't check as I'm using it to write this) my problem is my phone is letting me acess the net, send receive emails and use bbm, but can't send or receive texts or calls. I contacted o2 who said there's no prob with network and sim works in a different phone ok. I'm a pay as you go customer. I was looking for the same thing, to change imei to another BB curve I have that won't go on, but don't think that's gna happen. Ii checked status of unlocks/locks everything says disabled except network, that's saying inactive