Verification Involving PSTN Reachability: Requirements and Architecture Overview

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Last updated 2014-06-12 (latest revision 2013-12-09)
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The Session Initiation Protocol (SIP) has seen widespread deployment within individual domains, typically supporting voice and video communications. Though it was designed from the outset to support inter-domain federation over the public Internet, such federation has not materialized. The primary reasons for this are the complexities of inter-domain phone number routing and concerns over security. This document reviews this problem space, outlines requirements, and then describes a model and technique for inter-domain federation with SIP involving the Public Switched Telephone Network (PSTN), called Verification Involving PSTN Reachability (VIPR). VIPR addresses the problems that have prevented inter-domain federation over the Internet. It provides fully distributed inter-domain routing for phone numbers, authorized mappings from phone numbers to domains, a new technique for automated SIP anti-spam, and privacy of number ownership, all while preserving the trapezoidal model of SIP.


Mary Barnes (
Cullen Jennings (
Jonathan Rosenberg (
Marc Petit-Huguenin (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)