A Porting Authorisation Code (PAC) is a unique identifier used by some mobile network operators to facilitate mobile number portability. This code, typically nine characters long, allows users to retain their mobile telephone number when switching operators. When a customer wants to switch to a new service provider while keeping their existing phone number, they will need to request a PAC from their current provider. The PAC is then provided to the new service provider, who handles the transfer of the number. The PAC is valid for a period of 30 calendar days from the day of issue, and the customers request must be submitted to their new service provider within that time. The process of obtaining a PAC code has been made easier with the introduction of text-to-switch, allowing customers to immediately obtain and use their PAC code when switching mobile phone providers. Its important to note that PAC codes are free, and customers should not terminate their mobile phone contract until they have requested and used their PAC code to avoid losing their existing mobile phone number.