Page 1 of Orange network to o2 network help?

Hi. I would like to change from orange to o2 networkon my se k750i. So i ordered a free o2 sim card and it came yesterday. I put it in phone and have to activate it but it will not let me ring up to activate the sim card.
Is there anyway of activating it with out phoning up! :(

Two things.Is the phone unlocked? Secondly you might have to topup with £10 to get you going.Unless they have changed things recently,the O2 sim comes with a number so no need to register.
Cheers.