• [1] RFC 5621 - Message Body Handling in the Session Initiation Protocol (SIP) (2009-09-12 07:37:40 +09:00 版) http://tools.ietf.org/html/rfc5621#section-9.4
• [2] RFC 5621 - Message Body Handling in the Session Initiation Protocol (SIP) (2014-09-14 07:55:49 +09:00 版) http://tools.ietf.org/html/rfc5621#section-12.1