https://app.kbone.net/vault/rfc/docid/4130
RFC3773: High-Level Requirements for Internet Voice Mail
Network Working Group E. Candell Request for Comments: 3773 Comverse Category: Informational June 2004 High-Level Requirements for Internet Voice Mail Status of th...
https://app.kbone.net/vault/rfc/docid/4631
RFC4239: Internet Voice Messaging (IVM)
Network Working Group S. McRae Request for Comments: 4239 IBM Category: Standards Track G. Parsons Nortel Networks ...