Rashmi Bhardwaj | Blog,Protocol

SCCP is the abbreviation for Skinny client control protocol.

SCCP is a lightweight IP-based protocol for session signaling with Cisco Unified Communications Manager.It is used to control Cisco IP phones and other Cisco endpoint devices such as ATA 186/188.Like MGCP, SCCP devices report all actions to communication manager server which responds with the action device need to take. Interaction with IP phones such as lifting handset, digit dialing, and so on) causes skinny messages to be sent to call processing software, which then instructs device action to be taken. CallManager acts as a signaling proxy for calls initiated over other common protocol like H.323, SIP and MGCP. The major benefit is Cisco can deploy new features and capabilities without requiring any major revisions to industry standard protocol. But the drawback is it can only work with Cisco software or Cisco unified communication manager.

Examples of SCCP clients include –


  • Cisco 7900 series of IP phones,
  • Cisco IP Communicator softphone
  • 802.11b wireless Wireless IP Phone 7920,
  • Cisco Unity voicemail server.



Call States Sent to SCCP Endpoints by Cisco CallManager:-

This list defines the call states that are sent to SCCP endpoints, such as Cisco IP phones by Cisco CallManager in SCCP protocol. Cisco CallManager functions as an H.323 proxy. These are not the call states used in Cisco CallManager internally. Instead, they are the call states sent from Cisco CallManager and understood by the SCCP endpoints:

  • Off Hook
  • On Hook
  • Ring Out
  • Ring In
  • Connected
  • Busy
  • Line In Use
  • Hold
  • Call Waiting
  • Call Transfer
  • Call Park
  • Call Proceed
  • In Use Remotely
  • Invalid Number


References –



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