[upnunder]

Carphone Warehouse insist that you buy a top up with the phone as they wont get their commission from the network until the phone is topped up.

If they have over a certain percentage sold without top-up, they will get money clawed back from them by the networks, usually the full, unsubsidised cost of the handset.

This is also to avoid box breaking issues, where sim free phones are bought as PAYG phones, which are heavily subsidised by the networks, but never topped up or activated, then generally sent abroad to be sold.

I spent 3 years working for CPW, so dont really have any problems with them.