Method for routing a call

Claim 1

A method for routing a call to a called Subscriber having an assigned directory number, NXX-XXXX or NPA-NXX-XXXX, and having moved to a different location served by a switch having a different exchange code, NYY, and a line code YYYY, comprising the steps of: (a) dialing the directory number of the called Subscriber; (b) determining from the dialed number, whether the call is an intra-LATA call or a call to an exchange code (NXX) served by a local switch, (i) if the call is to an exchange code (NXX) served by the local switch, determining whether the dialed directory number is served by the local switch; and, (A) if the dialed directory number is served by the local switch, routing the call to the called Subscriber using the directory number; and, (B) if the dialed directory number is not served by the local switch, accessing a database external to the local switch to obtain routing information for the call; and, (ii) if the call is an intra-LATA call, determining based on an NPA code of the dialed directory number and the dialed exchange code NXX of the dialed directory number, whether the dialed exchange code supports local number portability, and if it does, then accessing the database external to the local switch to obtain routing information for the call; and wherein accessing the database external to the local switch comprises the steps of: (c) adding to the dialed directory number an NPA code if such NPA code is absent from the dialed directory number, to provide a database accessing number; (d) retrieving from the database, in response to the database accessing number, a corresponding number comprising an SPA code of the called Subscriber's service provider plus the NYY exchange code plus the line code YYYY, where an SPA code is a three digit designation code assigned to each one of a plurality of Local Service Providers within a common Numbering Plan Area (NPA), each one of the Local Service Providers being assigned a different SPA code in the common Numbering Plan Area (NPA); and (e) routing the call using the corresponding number.

Claim 2

A method for routing a call to a called Subscriber having an assigned directory number, NXX-XXXX or NPA-NXX-XXXX, and having moved to a different location served by a switch having a different exchange code, NYY, and a line code YYYY, comprising the steps of: (a) dialing the directory number of the called Subscriber; (b) determining from the dialed number, whether the call is an intra-LATA call or a call to an exchange code (NXX) served by a local switch, (i) if the call is to an exchange code (NXX) served by the local switch, determining whether the dialed directory number is served by the local switch; and, (A) if the dialed directory number is served by the local switch, routing the call to the called Subscriber using the directory number; and, (B) if the dialed directory number is not served by the local switch, accessing a database external to the local switch to obtain routing information for the call; and, (ii) if the call is an intra-LATA call, determining based on an NPA code of the dialed directory number and the dialed exchange code NXX of the dialed directory number, whether the dialed exchange code supports local number portability, and if it does, then accessing the database external to the local switch to obtain routing information for the call; and wherein accessing the database external to the local switch comprises the steps of: (c) adding to the dialed directory number an NPA code if such NPA code is absent from the dialed directory number, to provide a database accessing number; (d) retrieving from the database, in response to the database accessing number, a corresponding number comprising an SPA code of the called Subscriber's service provider plus the NYY exchange code plus the line code YYYY, where an SPA code is a three digit designation code assigned to each one of a plurality of Local Service Providers within a common Numbering Plan Area (NPA), each one of the Local Service Providers being assigned a different SPA code in the common Numbering Plan Area (NPA); and (e) routing the call using the corresponding number.

Claim 4

A method for routing a call to a called subscriber using a dialed number comprising NXX-XXXX or NPA-NXX-XXXX, the method comprising the steps of: (a) determining from the dialed number, whether: (1) the dialed number is served by a local switch serving a line from which the call is placed; or, (2) the call is an intra-LATA call and the dialed number is not served by the local switch; and, (i) if the dialed number is served by the local switch, then using the local switch to route the call to the called subscriber using the dialed number; (ii) if the call is an intra-LATA call and the dialed number is not served by the local switch, determining, based on an NPA code of the dialed number and the exchange code NXX of the dialed number, whether local number portability is available for the dialed number; (A) if local number portability is available for the dialed number, then accessing an External Local Number Portability Database using the dialed number to retrieve routing information comprising a Service Provider Area (SPA) code, an exchange code NYY and a line code YYYY, and routing the call using the routing information, where an SPA code is a three digit designation code assigned to each one of a plurality of Local Service Providers within a common Numbering Plan Area (NPA), each one of the Local Service Providers being assigned a different Service Provider Area (SPA) code in the common Numbering Plan Area (NPA); and, (B) if local number portability is not available for the dialed number, routing the call using the dialed number.

Claim 5

A method for routing a call to a called subscriber using a dialed number comprising NXX-XXXX or NPA-NXX-XXXX, the method comprising the steps of: (a) determining from the dialed number, whether: (1) the dialed number is served by a local switch serving a line from which the call is placed; or, (2) the call is an intra-LATA call and the dialed number is not served by the local switch; and, (i) if the dialed number is served by the local switch, then using the local switch to route the call to the called subscriber using the dialed number; (ii) if the call is an intra-LATA call and the dialed number is not served by the local switch, determining, based on an NPA code of the dialed number and the exchange code NXX of the dialed number, whether local number portability is available for the dialed number; (A) if local number portability is available for the dialed number, then accessing an External Local Number Portability Database using the dialed number to retrieve routing information comprising a Service Provider Area (SPA) code, an exchange code NYY and a line code YYYY, and routing the call using the routing information, where an SPA code is a three digit designation code assigned to each one of a plurality of Local Service Providers within a common Numbering Plan Area (NPA), each one of the Local Service Providers being assigned a different Service Provider Area (SPA) code in the common Numbering Plan Area (NPA); and, (B) if local number portability is not available for the dialed number, routing the call using the dialed number.