Portability of mobile numbers is a feature that enables a customer of a cell phone or smartphone to change the telephone carrier and maintain the same phone number.
For instance, in India, the method of mobile number portability has been made as easy as possible. The customer must simply send a text message (SMS) that says PORT to 1900 from their phone. The current company will give a special port code to the customer, which will be exchanged by the customer with their major phone.
The routing of calls or mobile messages (SMS, MMS) to a number after it has been ported is a major technical component of MNP. There are different kinds of call routing processes globally, but the use of a central database (CDB) of port numbers is the international and European best practice. A network operator makes copies of the CDB and asks it to figure out which network a call should be sent to.
This ACQ/CDB method of call routing is the basis of a majority of the existing and upcoming MNP systems worldwide. The UK, where after a number has been ported, calls to that number are still routed through the donor network, is one of the very few countries not to use ACQ/CDB. This is often referred to as "indirect routing" and is extremely inefficient as transmission and switching power is wasteful. Indirect routing often ensures that if the donor system develops a malfunction or goes out of service, clients who have ported numbers out of that network will lose incoming calls to their numbers because of its donor-dependent nature.
For the telecom markets, MNP is critical because it eliminates an obstacle to switching that could hold those with a lot of equity behind a high switching barrier, especially business users. The particular benefit to challenger carriers against dominant incumbents is the reduction in barriers to switching. Usually, a rise in churn follows when MNP is applied in a country.