- Skinny Call Control Protocol
SCCP (Skinny Call Control Protocol) is a proprietary terminal control protocol originally developed by Selsius Corporation. It is now owned and defined by
Cisco Systems, Inc.as a messaging set between a skinny client and the Cisco CallManager. Examples of skinny clients include the Cisco 7900 series of IP phone such as the Cisco 7960, Cisco 7940, Cisco IP Communicatorsoftphone and the 802.11bwireless Cisco 7920, along with Cisco Unityvoicemail server. Skinny is a lightweight protocol which allows for efficient communication with Cisco CallManager. [ [http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a0080624977.shtml Call states sent to SCCP endpoints by Cisco CallManager] ] CallManager acts as a signaling proxy for call events initiated over other common protocols such as H.323, SIP, ISDNand/or MGCP.
A skinny client uses
TCP/IPto and from one or more Call Managers in a cluster. RTP/UDP/IP is used to and from a similar skinny client or H.323 terminal for the bearer traffic (real-time audio stream). 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.
Cisco acquired SCCP technology when it acquired Selsius Corporation in 1998. [ [http://newsroom.cisco.com/dlls/fspnisapi6d14.html Cisco Systems acquisition of Selsius Systems] ] As a remnant of the Selsius origin of the current Cisco IP phones, the default device name format for registered Cisco phones with CallManager is SEP -- as in "Selsius Ethernet Phone" -- followed by the
Other companies like
Symbol Technologiesand SocketIPhave implemented this protocol in VoIP Terminals (phones) and Media Gateway Controllers or Softswitches. Open Source implementations of SCCP/Skinny exist and are now part of the Asterisk (PBX)system.
A company named [http://www.ipblue.com/ IPBlue] has created a software phone (
soft phone) which uses SCCP for signaling, too. This phone in fact appears to the Cisco CallManagerserver as a 7960 hardware phone.
In addition, Cisco has come out with its own version of a skinny softphone called Cisco IP Communicator as well as SIP-based softphone called Cisco Unified Personal Communicator. Previously, Cisco had a JTAPI/CTI version of a softphone called Cisco IP Softphone.
[http://www.cisco.com/en/US/tech/tk652/tk701/tk589/tsd_technology_support_sub-protocol_home.html Skinny Call Control Protocol (SCCP) - Cisco Systems]
[http://hisown.com/Talks/VoIP%20-%20Excerpt%20(SCCP).pdf Skinny Call Control Protocol (SCCP) - Fragment of a VoIP course dealing with SCCP, with sample captures]
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