I have kept my o2 number for almost 20 years. it use to be a contract number but I switch it to pay as you go. o2 encouraged me to switch back to contract, I agreed on the condition I get to keep my number. after switching to contract, what I thought was a new SIM but the same old number, o2 changed my old number and now I'm having problems not receiving phone calls from all who only this contact number.
even though I have two numbers, the old number is the only one I know from memory.
