Mobile number portability

Mobile number portability (MNP) enables mobile telephone users to retain their mobile telephone numbers when changing from one mobile network operator to another.

General overview

MNP [Mobile number portability]is implemented in different ways across the globe. The international and European standard is for a customer wishing to port his/her number to contact the new provider (Recipient) who will then arrange necessary process with the old provider (Donor). This is also known as 'Recipient-Led' porting. The UK is the only country to not implement a Recipient-Led system, where a customer wishing to port his/her number is required to contact the Donor to obtain a Porting Authorisation Code (PAC) which he/she then has to give to the Recipient. Once having received the PAC the Recipient continues the port process by contacting the Donor. This form of porting is also known as 'Donor-Led' and has been criticised by some industry analysts as being inefficient. It has also been observed that it may act as a customer deterrent as well as allowing the Donor an opportunity of 'winning-back' the customer. This might lead to distortion of competition, especially in the markets with new entrants that are yet to achieve scalability of operation.

Technical details

A significant technical aspect of MNP (Mobile Number Portability) is related to the routing of calls or mobile messages (SMS, MMS) to a number once it has been ported. There are various flavours of call routing implementation across the globe but the international and European best practice is via the use of a central database (CDB) of ported numbers. Network operator makes copies of CDB and queries it to find out which network to send a call to. This is also known as All Call Query (ACQ) and is highly efficient and scalable. Majority of the established and upcoming MNP systems across the world are based on this ACQ/CDB method of call routing. One of the very few countries to not use ACQ/CDB is the UK where calls to a number once it has been ported are still routed via the Donor network. This is also known as 'Indirect Routing' and is highly inefficient as it is wasteful of transmission and switching capacity. Because of its Donor dependent nature, Indirect Routing also means that if the Donor network develops a fault or goes out of business, the customers who have ported out of that network will lose incoming calls to their numbers. The UK telecoms regulator Ofcom completed its extended review of the UK MNP process on 29 November 2007 and mandated that ACQ/CDB be implemented for mobile to mobile ported calls by no later than 1 September 2009^{[needs update]},

Prior to March 2008 it took a minimum of 5 working days to port a number in the UK compared to 2 hours only in USA, as low as 20 minutes in the Republic of Ireland, 3 minutes in Australia and even a matter of seconds in New Zealand. On 17 July 2007, Ofcom released its conclusions from the review of UK MNP and mandated reduction of porting time to 2 working days with effect from 1 April 2008. On 29 November 2007, Ofcom completed its consultation on further reduction to porting time to 2 hours along with recipient led porting and mandated that near-instant (no more than 2 hours) recipient led porting be implemented by no later than 1 September 2009.

In a decentralised model of MNP, a FNR (Flexible Number Register) may be used to manage a database of ported out/ported in numbers for call routing

Number Lookup Services

Service providers and carriers who route messages and voice calls to MNP-enabled countries might use HLR query services to find out the correct network of a mobile phone number. A number of such services exist, which query the operator's home location register (HLR) over the SS7 signalling network in order to determine the current network of a specified mobile phone number prior to attempted routing of messaging or voice traffic.