New Parameters for the 'tel' URL to Support Number Portability and Freephone Service
NeuStar, Inc.
This document proposes three extensions to the 'tel' Uniform Resource Locator for supporting number portability (NP) and freephone service. Those proposed extensions allow the Session Initiation Protocol to carry the tel URL or to convert the tel URL to the SIP URL so as to support NP and freephone service. The proposed extensions allow the SIP protocol to be used to derive the routing number for the ported geographical numbers, identify the freephone service provider/carrier or the Plain Old Telephone Service (POTS) number for a freephone number, and carry the NP- and freephone-related information in the SIP messages.