I switched from three couple of weeks ago, wanting to keep my old number. Transition went fine, after few days I noticed I was not receiving any phone calls or texts. I was able to call though. I called the customer service on Saturday and after being put on hold twice they hung up. Called again after 1 day and apparently the sim was disconnected ! Wow O2 what a move...now back to square one where I can only make phone calls but not received them nor any messages. Way forward to lose a client.