Section 7.6. Cisco SCCP

7.6. Cisco SCCP

SCCP is a signaling protocol developed by Cisco. Though proprietary, open implementations of Cisco SCCP do exist. There is an SCCP module for Asterisk that is free and open source. The Skinny Client Control Protocol is so named because it is a far less ambitious suite than H.323. In this regard, SCCP is more akin to IAX.

Like IAX, SCCP is a leg-only signaling solution; it doesn't dictate how multiple legs of a single call path should be conducted as H.323 and SIP do. It doesn't mention anything about proxies either. In fact, SCCP is used in tandem with H.323 in most implementations, because many of the features SCCP does not implement, such as H.245, are required to provide a full PBX solution for a group of IP phones. So, in an SCCP environment, call setup and capabilities negotiation still occur by way of H.323, but these functions reside within the softPBX rather than being negotiated directly between endpoints.

The Cisco softPBX is called CallManager, and it provides the best reference implementation of SCCP. Vovida.org, the home of the open source VOCAL project sponsored by Cisco, has more detailed information and open reference projects on SCCP. There's also an open source SCCP signaling module for Asterisk.