coderus,

Isn't that for re-registering? On my brother's SGS2, he registered with 1 number, plucked out the sim and it still works over WiFi then put in another sim and it still works with his number being shown to others the original number he used to register...

In fact, the number he used to register is lost since many months still no issue...

I think even on Wazapp once you are registered with 1 number you can pluck out the sim and swap it won't detect a change unless you have to re-register (this is what I think not sure of as I don't use it so please check for yourself)...