https://app.knowbase.one/vault/rfc/docid/3159
RFC2848: The PINT Service Protocol: Extensions to SIP and SDP for IP Access to Telephone Call Services
Network Working Group S. Petrack Request for Comments: 2848 MetaTel Category: Standards Track L. Conroy Siemens Roke Manor Research ...
https://app.knowbase.one/vault/rfc/docid/3677
RFC3298: Service in the Public Switched Telephone Network/Intelligent Network (PSTN/IN) Requesting InTernet Service (SPIRITS) Protocol Requirements
Network Working Group I. Faynberg, Editor Request for Comments: 3298 Lucent Technologies Category: Informational J. Gato Vodaphone ...