Network Working Group B. Foster Request for Comments: 3661 C. Sivachelvan Updates: 3435 Cisco Systems Category: Informational December 2003 Media Gateway Control Protocol (MGCP) Return Code Usage Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document provides implementation guidelines for the use of return codes in RFC 3435, Media Gateway Control Protocol (MGCP) Version 1.0. Return codes in RFC 3435 do not cover all possible specific situations that may ever occur in a gateway. That is not possible and not necessary. What is important is to ensure that the Call Agent that receives a return code behaves appropriately and consistently for the given situation. The purpose of this document is to provide implementation guidelines to ensure that consistency. Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Document Organization . . . . . . . . . . . . . . . . . 2 2. Return Code Usage . . . . . . . . . . . . . . . . . . . . . . 2 2.1. Return Code Categories. . . . . . . . . . . . . . . . . 2 2.2. Return Code Situations and Categories . . . . . . . . . 3 2.3. Summary of Return Code Categories . . . . . . . . . . . 19 3. Additional Guidelines . . . . . . . . . . . . . . . . . . . . 21 3.1. Gateway Recommendations . . . . . . . . . . . . . . . . 21 3.2. Call Agent Recommendations. . . . . . . . . . . . . . . 21 4. Security Considerations . . . . . . . . . . . . . . . . . . . 22 5. Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . 22 6. Normative References. . . . . . . . . . . . . . . . . . . . . 22 7. Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . 23 8. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 24 Foster & Sivachelvan Informational