This chapter describes telephony protocols, including the Media Gateway Control Protocol (MGCP), the Session Initiation Protocol (SIP), H.323 (H.225, H.245, RAS), the Skinny Client Control Protocol (SCCP), and TDM/analog signaling protocols.
SCCP is a Cisco proprietary master/slave protocol that CUCM and other call agents can use to communicate with devices and endpoints, such as Cisco IP phones. One advantage of SCCP is that it is flexible and allows features to be easily added.
SCCP uses TCP ports 2000 (SCCP) and 2443 (Secure SCCP [SCCPS]). Skinny gateway (analog) uses TCP port 2001 and skinny gateway (digital) uses TCP port 2002.
Figure 3-1 illustrates an SCCP call between two phones ...