How do phone companies let you keep the same phone number when you switch over to them?

Question

How do phone companies let you keep the same phone number when you switch over to them?

In: 1

Answer 1

the sim card has its own id unrelated to the actual phone number. when you’re registered with the network, the operator says “ok so sim number X shoud be associated with phone number Y”

If you changed carriers your number will simply be associated with the new sim’s id