jdrosen.net Cisco Stonyfish One of the main challenges in inter-domain federation of Session Initiation Protocol (SIP) calls is that many domains continue to utilize phone numbers, and not email-style SIP URI. Consequently, a mechanism is needed that enables secure mappings from phone numbers to domains. The main technical challenge in doing this securely is to verify that the domain in question truly is the "owner" of the phone number. This specification defines the PSTN Validation Protocol (PVP), which can be used by a domain to verify this ownership by means of a forward routability check in the PSTN. Legal This documents and the information contained therein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION THEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.