The present invention is directed to a method for providing a service provider number portability of a mobile phone number in which it is possible to change a mobile phone service provider without changing a mobile directory number (MDN) in a communication environment where the phone service providers use different intelligent network protocols. In the present invention, the intelligent network calls which uses different protocols are processed using a number portability database which supports the multi-protocols in order to change the service provider between the mobile phone service providers in which the mobile phone subscribers use different intelligent protocols. Therefore, since the mobile phone number portability providing method according to the present invention is capable of processing all intelligent network calls transferred from the service providers which use different protocols, it is possible to overcome the problems such as, building additional number portability database in the case that the intelligent network protocols are different, and installing a plurality of protocols in all service switching point in the service provider network. In this way, it becomes possible to decrease the cost of the number portability, and the network operation gets easier if all service providers co-use the number portability database of the mobile phone.