SCCP is a half-proprietary VoIP terminal control protocol defined by Cisco Systems, Inc., who uses it to control their Cisco 7960 and 7940 voice over IP terminals (phones). It is rumoured to be a descendant of IPDC or SGCP.
Other companies like Symbol Technologies and SocketIP have implemented this protocol in VoIP Terminals (phones) and Media Gateway Controllers or Softswitches.
A company named IPBlue has created a software phone (soft phone) which uses SCCP for signaling, too. This phone in fact appears to the Cisco CallManager server as a 7960 hardware phone.