* 仕様書

[REFS[
- [1] [CITE@en[RFC 6086 - Session Initiation Protocol (SIP) INFO Method and Package Framework]] ([TIME[2014-09-21 12:01:46 +09:00]] 版) <http://tools.ietf.org/html/rfc6086#section-4.2.2>
- [2] '''[CITE@en[RFC 6086 - Session Initiation Protocol (SIP) INFO Method and Package Framework]] ([TIME[2014-09-21 12:01:46 +09:00]] 版) <http://tools.ietf.org/html/rfc6086#section-4.3.1>'''
- [3] [CITE@en[RFC 6086 - Session Initiation Protocol (SIP) INFO Method and Package Framework]] ([TIME[2014-09-21 12:01:46 +09:00]] 版) <http://tools.ietf.org/html/rfc6086#section-11.5>
]REFS]