Many years ago, probably about 17 or 18 years, my mother and I both had Nokia 3310s on O2. I was about 12 or 13 and we had mobile numbers only two digits different. For whatever reason, my SIM card got scratched and I got a new number and went to another network. It was back in the day when everybody was on Pay and Go so it's not like I had a contract to cancel and I was very young so I didn't think anything about moving on. I was wondering apart from the obvious of calling the number to see if anybody answers, is there any way to checking if it's in use and if it isn't, getting the number back? Obviously if it is, I'll drop it and move on. But was curious. It was an O2 number. What do you think are the chances? Should I contact O2 directly?
