Number portability services or technology that enables users to keep your phone number after moving from services provider to another which have evolved in the area of quality of services and make the client satisfaction or customer is the upper hand. And sparked completion among service providers to compete by providing better service to customers ,otherwise the customer will move easily to any other service provider offer best Qos. Qos include availability, speed (band width data rate) and delay, as well as in the prices of the services and application available. In this paper we will take the implementation procedure of this service in term of technical side from the point of view of service provider. Will take company in the field telecommunication in Sudan ZAIN as an example.