You dig an old SIM card out of a drawer, pop it into your phone, and wait for the number to come back to life.
Instead, you find that the number now belongs to someone else, and you’re suddenly wondering how your old digits moved on without you.
It feels a bit personal, but there’s a simple reason behind it. South African networks recycle cell numbers all the time, and there’s a whole system behind why they do it and how it works.
Why cell numbers get recycled
South Africa uses a fixed numbering system. Networks get certain number ranges and, once those fill up, there’s no magical “add more numbers” button. Recycling is the only way to keep the system from grinding to a halt.
Add to that the reality of local SIM behaviour: many people hop between networks for better data specials, and prepaid SIMs are often treated like disposable cutlery.
A number can be alive one month and forgotten the next. Networks can’t let millions of abandoned numbers sit around forever, so they reclaim and reuse them.
There’s also the regulatory side. The Independent Communications Authority of South Africa (ICASA) expects networks to manage number resources responsibly. It’s a bit like being told to clean your room, but on a national scale.
How it actually works
When you stop using a SIM, the number doesn’t disappear instantly.
It usually goes quiet for a few months while the network waits to see if you’ll return. Sometimes even connecting to mobile data for a moment is enough to prove you’re still alive.
If nothing happens, the network puts the number into a kind of digital time-out.
It sits there for a quarantine period so old billing issues, porting requests, and other admin drama can settle.
Once that’s done, the number goes back into circulation. A new user might get it when they activate a fresh prepaid pack or sign a new contract. For them, it’s a shiny new start. For the number, it’s reincarnation.
What this means for you
If your old number gets reassigned, the new owner might receive a few stray calls or messages meant for you.
Usually it’s harmless, an old auntie trying to ask about Sunday lunch or a courier insisting your parcel is outside the gate.
The bigger concern is online accounts. Many services rely on SMS codes for login or verification. If you don’t update your number before abandoning it, someone else could receive those codes once the number is recycled.
The easiest fix is to update your number everywhere that matters before letting go of an old SIM. Banking apps, social accounts, email, anything with an OTP – give them your new details.
If you want to keep a number alive, make a call, send a message, or use a little data every few months. Networks just need proof you’re still around.
