ETSI TS 122 066 defines the stage one description of the Support of Mobile Number Portability between networks in the same country as well as North America cross-sector portability (i.e.,. number portability between fixed and 3GPP system). Stage one is an overall service description, primarily from the service subscriber's and user's points of view, but does not deal with the details of the human interface itself.

Mobile Number Portability (MNP) is applicable only to those telecommunication services identified by an MSISDN.

This specification includes information applicable to network operators, service providers and terminal, switch and database manufacturers.

This specification contains the core requirements for the Support of Mobile Number Portability between network operators in the same country as well as North America cross-sector portability which are sufficient to provide a complete service.

Other cross-sector portability options (e.g. number portability between fixed and mobile networks outside the North American Region) are outside the scope of this technical specification. It is highly desirable however, that technical solutions for MNP should be sufficiently flexible to allow for possible enhancements, e.g. cross-sector number portability, and MNP between analogue and digital mobile networks. Additional functionalities not documented in this specification may implement requirements which are considered outside the scope of this specification. This additional functionality may be on a network-wide basis, nation-wide basis or particular to a group of users. Such additional functionality shall not compromise conformance to the core requirements of the service.

Porting between Service Providers (i.e. service provider portability) which does not involve a change of Network Operator is outside the scope of this specification.

The relationship between Service Providers and Network Operators is outside the scope of this specification.

The relationship between a Service Provider and subscriber is outside the scope of this specification. The interface between the User Equipment (UE) and any external applications are outside the scope of this specification. Charging principles are outside the scope of this specification except where explicitly stated in the text.