A method for enabling a plurality of Local Service Providers within common Numbering Plan Area (NPA) to serve Subscribers of the plurality Local Service Providers. The method includes the step of assigning to each Subscriber of a Local Service Provider within the common NPA a unique three...http://www.google.de/patents/US5748724?utm_source=gb-gplus-sharePatent US5748724 - Method for transferring a subscriber to a new local service provider
