I was away from the country for about 2years and after I returned I tried using my old MTN Sim card but it wasn't working. I went to the closest MTN office to complain and I was told that my number had been recycled. According to them, when a Sim card stays inactive for 3months, it is recycled and the number is given to someone else. This means that all my correspondents have been going to someone else, including my bank account alerts.
I wonder how security conscious this policy is. The least they could do is inform me by email so I can stop my alerts being that they have all their customer's email following the Sim registration exercise.