What is MNP or Mobile Number Portability?
MNP is a feature or service to a mobile subscriber, by which a mobile subscriber can change a serving mobile operator, without changing mobile number or MSISDN. The full form of MNP is mobile number portability. Before MNP, if a subscriber wants to use the services of another mobile operator then he has to purchase a new sim card with the new mobile number. Most of the people carries a mobile number which is very old or have been updated at multiple places e.g banks, on web sites etc. This makes changing mobile number to a difficult task. But at the same time , every one wants to use better services from any of the mobile operator in that area.
With mobile number portability, the pain of changing a mobile number is gone. Now you can keep same number , but can change mobile operator to enjoy better services. Full form mentions , portability. So changing mobile operator is called porting mobile number from one service provider to other.
MNP and National Roaming:
There are countries like India, where roaming is applicable to a mobile number if it changes a significant location with in a country. E.g if some one is living in Delhi and his employment location changes to Pune. Earlier to MNP, if a person want to keep the same number, he has to but at least roaming pack to reduce the phone bills. With MNP, mobile number can be changed from one location to other with in a country. So that national roaming charges can be removed.
Subscriber Profile Migration:
A subscriber profile is configured in the HLR. HLR is database along with a software application. It keeps the subscriber record. When a new sim card is purchased. The HLR is update for new sim card with new IMSI. After MNP the imsi changes of subscriber. The new imsi, belongs to new mobile operator. The HLR of new operator configured with new imsi with the older msisdn. All services are control from new HLR.
For porting a number to other mobile operator, there is a mnp process. The mnp process involves, deactivating and removing subscriber from current service provider and to configure and activate from new service provider. Before moving to new one, the bills from existing service provider should be cleared.
Read the porting requirements carefully for the new mobile operator.
If applicant is eligible , the signed copy of document is required by the mobile operator.
New mobile operator issues the sm card to the subscriber.
Old sim card gets deactivated and new sim cards cards gets activated.
For more details in India you can visit TRAI website.
Routing in mobile network after MNP:
Before MNP, from a mobile number or MSISDN, the serving operator can be identified. From country code and from network code present in MSISDN, a call or sms can be sent to the serving mobile network operator. For example, if a Vodafone subscriber dials a Airtel New Delhi India subscriber. Based on country code , the message for call first reaches to the India, then based on network code call reaches to the Airtel Delhi GMSC.
After the MNP, a mobile number and network operator don't have any correlation. This leads to maintain a MNP database. When a call or sms originates , it queries to MNP database. Then routes to the serving operator. For example , if a subscriber is called , which is now an Airtel subscriber after MNP, before MNP, it was a Vodafone subscriber. Call first reaches to the Vodafone , then a MNP database lookup is performed and call is routed to the Airtel.