■ RFC1889 RTP: A Transport Protocol for Real-Time Applications.
■ RFC2543 SIP: Session Initiation Protocol
■ RFC2833 RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals
■ RFC2880 Internet Fax T.30 Feature Mapping
■ RFC2976 The SIP INFO Method
■ RFC3261 SIP: Session Initiation Protocol
■ RFC3262 Reliability of Provisional Responses in Session Initiation Protocol (SIP)
■ RFC3263 Session Initiation Protocol (SIP): Locating SIP Servers
■ RFC3264 An Offer/Answer Model with Session Description Protocol (SDP)
■ RFC3265 Session Initiation Protocol (SIP)-Specific Event Notification
■ RFC3311 The Session Initiation Protocol (SIP) UPDATE Method
■ RFC3323 A Privacy Mechanism for the Session Initiation Protocol (SIP)
■ RFC3325 Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity    within Trusted Networks
■ RFC3362 Real-time Facsimile (T.38) - image/t38 MIME Sub-type Registration
■ RFC3515 The Session Initiation Protocol (SIP) Refer Method
■ RFC3550 RTP: A Transport Protocol for Real-Time Applications. July 2003
■ RFC3665 Session Initiation Protocol (SIP) Basic Call Flow Examples
■ RFC3824 Using E.164 numbers with the Session Initiation Protocol (SIP)
■ RFC3841 Caller Preferences for the Session Initiation Protocol (SIP)
■ RFC3842 A Message Summary and Message Waiting Indication Event Package for the    Session Initiation Protocol (SIP)
■ RFC3891 The Session Initiation Protocol (SIP) "Replaces" Header
■ RFC3892 The Session Initiation Protocol (SIP) Referred-By Mechanism
■ RFC3960 Early Media and Ringing Tone Generation in the Session Initiation Protocol (SIP)
■ RFC3986 Uniform Resource Identifier (URI): Generic Syntax
■ RFC4028 Session Timers in the Session Initiation Protocol (SIP)
■ RFC2327 SDP: Session Description Protocol
■ Draft-ietf-sipping-service-examples-08 for call features

■ RFC318 Telnet Protocols
■ RFC791 Internet Protocol
■ RFC792 Internet Control Message Protocol
■ RFC793 Transmission Control Protocol
■ RFC768 User Datagram Protocol
■ RFC826 Ethernet Address Resolution Protocol
■ RFC959 File Transfer Protocol
■ RFC1034 Domain Names - concepts and facilities
■ RFC1035 Domain Names - implementation and specification
■ RFC1058 Routing Information Protocol
■ RFC1305 Network Time Protocol (NTP)
■ RFC1349 Type of Service in the Internet Protocol Suite
■ RFC1350 The TFTP Protocol (Revision 2)
■ RFC1661 The Point-to-Point Protocol (PPP)
■ RFC1738 Uniform Resource Locators (URL)
■ RFC2854 The 'text/html' Media Type
■ RFC2131 Dynamic Host Configuration Protocol
■ RFC2453 RIP Version 2
■ RFC2474 Definition of the Differentiated Services Field (DS Field)
■ RFC2516 A Method for Transmitting PPP Over Ethernet
■ RFC2616 Hypertext Transfer Protocol - HTTP/1.1
■ RFC2617 HTTP Authentication: Basic and Digest Access Authentication
■ RFC2637 Point-to-Point Tunneling Protocol
■ RFC2766 Network Address Translation - Protocol Translation(NAT-PT)
■ RFC2916 E.164 number and DNS
■ RFC3022 Traditional IP Network Address Translator
■ RFC3489 STUN - Simple Traversal of User Datagram Protocol (UDP)Through Network    Address Translators (NATs)
■ RFC3525 DigitMap
■ UPnP Device Architecture Version 1.0