This brief article explains the function of a SIM card and how to perform a SIM swap.
An important concept to understand that can be very helpful is that a phone number is associated with a SIM card and not a phone (device). When this is understood, it answers the question to the following scenario:
An individual has an active Z1 device/phone number and just received a new Z2 phone in the mail. How would this individual transfer the phone number from the Z1 to the new Z2?
Answer 1: This individual could simply insert the active SIM card from the Z1 into the Z2. The Z2 now has the phone number.
Why? Because the active phone number was housed with the SIM card and not the device.
Answer 2: Perform a SIM swap.
A SIM swap assigns a phone number to a different (many times new) SIM card. This is done inside your MyAccount:
A SIM swap is also appropriate when receiving a new SIM card in the mail for example. The phone number must be associated with the SIM card before it will work when the SIM is inserted into the Gabb phone.