The Skinny Client Control Protocol (SCCP) is a proprietary network terminal control protocol originally developed by

Selsius Systems Selsius Systems was a telecommunications company in Dallas, Texas that developed and marketed some of the first IP telephony gear. It was co-founded by Richard Platt and David Tucker. Selsius was incorporated in 1997 and acquired by Cisco Syste ...

, which was acquired by

Cisco Systems Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, ...

in 1998. SCCP is a lightweight IP-based protocol for session signaling with Cisco Unified Communications Manager, formerly named ''CallManager''. The protocol architecture is similar to the

media gateway control protocol architecture The media gateway control protocol architecture is a methodology of providing telecommunication services using decomposed multimedia gateways for transmitting telephone calls between an Internet Protocol network and traditional analog facilities of ...

, in that is decomposes the function of media conversion in telecommunication for transmission via an

Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. ...

network into a relatively low-intelligence customer-premises device and a call agent implementation that controls the CPE via signaling commands. The call agent product is Cisco CallManager, which also performs as a signaling proxy for call events initiated over other common protocols such as

H.323 H.323 is a recommendation from the ITU Telecommunication Standardization Sector (ITU-T) that defines the protocols to provide audio-visual communication sessions on any packet network. The H.323 standard addresses call signaling and control, mu ...

, and

Session Initiation Protocol The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telepho ...

(SIP) for

voice over IP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...

, or

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work ...

for the

public switched telephone network The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telep ...

Protocol components

An SCCP client uses

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the su ...

to communicate with one or more Call Manager applications in a cluster. It uses the

Real-time Transport Protocol The Real-time Transport Protocol (RTP) is a network protocol for delivering audio and video over IP networks. RTP is used in communication and entertainment systems that involve streaming media, such as telephony, video teleconference applicati ...

(RTP) over UDP-transport for the bearer traffic (real-time audio stream) with other Skinny clients or an H.323 terminal. SCCP is a stimulus-based protocol and is designed as a communications protocol for hardware endpoints and other embedded systems, with significant CPU and memory constraints. Some Cisco analog media gateways, such as the VG248 gateway, register and communicate with Cisco Unified Communications Manager using SCCP.

Origin

Cisco acquired SCCP technology when it acquired Selsius Corporation in 1998. For this reason the protocol is also referred to in Cisco documentation as the Selsius Skinny Station Protocol. Another remnant of the origin of the Cisco IP phones is the default device name format for registered Cisco phones with CallManager. It is ''SEP'', as in ''Selsius Ethernet Phone'', followed by the

MAC address A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking te ...

. Cisco also has marketed a Skinny-based softphone called Cisco IP Communicator.

Client examples

Examples of SCCP client devices include the Cisco 7900 series of IP phones, Cisco IP Communicator softphone, and the 802.11b wireless Wireless IP Phone 7920, along with Cisco Unity voicemail server.

Other implementations

Other companies, such as Symbol Technologies, SocketIP, and

Digium Digium, Inc. is a communications technology company based in Huntsville, Alabama, and since 2018, a subsidiary of Sangoma Technologies Corporation. The company makes VoIP business phone systems, IP phones, and hardware products. It was founded ...

, have implemented the protocol in VoIP terminals and IP phones,

media gateway controller The media gateway control protocol architecture is a methodology of providing telecommunication services using decomposed multimedia gateways for transmitting telephone calls between an Internet Protocol network and traditional analog facilities of ...

s, and

softswitch A softswitch (''software switch'') is a call-switching node in a telecommunications network, based not on the specialized switching hardware of the traditional telephone exchange, but implemented in software running on a general-purpose computing ...

es. An open source implementation of a call agent is available in the

Asterisk The asterisk ( ), from Late Latin , from Ancient Greek , ''asteriskos'', "little star", is a typographical symbol. It is so called because it resembles a conventional image of a heraldic star. Computer scientists and mathematicians often voc ...

and

FreeSWITCH FreeSWITCH is free and open-source server software for real-time communication applications, including WebRTC, video, and voice over Internet Protocol (VoIP). It runs on Linux, Windows, macOS, and FreeBSD. FreeSWITCH is used to build private bran ...

systems. IPBlue provides a soft phone that emulates a Cisco 7960 telephone. Twinlights Software distributes a soft phone implementation for Android-based devices.http://www.twinlightssoftware.com/ Twinlights Software The Cisco Unified Application Environment, the product acquired by Cisco when they purchased

Metreos Metreos was a software company that created and sold development and runtime tools for creating voice over Internet Protocol software applications. The company was founded by Louis Marascio and Mark Richards and was based in Austin, Texas, United ...

supports using SCCP to emulate Cisco 7960 phones allowing applications to access all Cisco line-side features.

References

{{Reflist VoIP protocols Cisco protocols Application layer protocols

Protocol components

Origin

Client examples

Other implementations

See also

References