3.8 Phone Number Resolution Extensions

[RFC3966] defines a notion of a Local Number as a phone number that is only valid within a certain geographical area or certain part of the telephony network. As specified in [RFC3966] section 5.1.5, Local Numbers SHOULD only be used in the environment where all local entities can successfully set up the call by passing this Local Number to dialing software.

This protocol provides a way to create such an environment, and employs a notion of location profile to describe it. Each location profile description carries a set of translation rules that resolve partially specified (local) numbers to identifiers which either route to unique enterprise users or form unique numbers in public telephone networks as defined by International Telecommunications Union Recommendation, contained in [E164]. A translation rule, in turn, is a tuple consisting of the regular expression that matches a subset of local numbers and a replacement pattern that provides an identifier that is no longer tied to a geographical area or part of the telephony network. This type of replacement identifier can be used for routing to a specific enterprise user or for identifying a subscriber in the public telephone network. The regular expressions and replacement patterns are based on .NET Regular Expression Language, as specified in [MC-RegEx]. In addition to defining the location profiles and translation rules that comprise them, this protocol describes a protocol that can be used by the protocol clients to obtain these profiles from the server.