Contract renewal cancellation while keeping my phone number with a prepaid plan

Hi,

I intend to cancel the renewal of my DSL and my phone contracts (which end next January) and will therefore send a letter to O2 soon.

Thence I wish to take an O2 prepaid plan, with the same phone number as I have now. Is it possible? I saw it is possible to port a number from another phone provider (for a fee..!) however given that my current plan is at O2 already I'd like to know, is the procedure the same? The plan I'm interested in is the O2 prepaid basic (ie the cheapest one).

Thank you!