Mobile Number Portability (MNP) is the industry agreed process by which a customer can switch from one network operator to another and take their existing mobile number with them, for example from Orange to O2.
Contact your current network provider and ask for a Porting Authorisation Code (PAC).
The PAC number is your authority to request a transfer and will allow the Network you wish to move to, to request your number be transferred to them.
Your current Service Provider can only refuse to issue a PAC for the following two reasons:
Your PAC number is only valid for 30 calendar days; your request must be submitted to the new network within that period.
For most networks you are connecting to, it is possible to port your number after connection. When your new handset arrives it will make and receive calls with a temporary number. Simply call the new network customer services and pass them the PAC number you have. The network will arrange port dates with your old network, and on the agreed date your number will be moved across to the new handset.
After requesting a PAC number from your existing network, they are required to supply it to you within a few days (providing you have fulfilled the obligations of your contract) however some networks will supply it immediately. After relaying your PAC number to your new network, the porting process should be completed within 2 working days. Mobile networks vary.
The following points should be read carefully as they may apply to your circumstances: