Mobile number portability, mobile number porting and MNR these are the same terminology in mobile word.
The meaning of Mobile number portability is that allow any user to change current mobile service provider to another mobile service provider by using same mobile number which you want to transfer for the batter service so it allows to customer to change mobile network with excreting mobile number.
Currently in India mobile number portability service available in a same circle means customer can choose other mobile network in same state. One State to another state is not allow at this time.
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