Signaling Connection Control Part (SCCP) provides connectionless and connection-oriented network services above the MTP Level 3. While MTP Level 3 provides point codes to allow messages to be addressed to specific signaling points, SCCP provides subsystem numbers to allow messages to be addressed to specific applications (called subsystems) at these signaling points. Connectionless SCCP is used as the transport layer for TCAP-based services like free-phone, private virtual number, wireless roaming etc. Connection-oriented and connectionless SCCP is used in BSSAP to support signaling messages between a GSM Base Station (BS) and a Mobile service Switching Center (MSC). The BSSAP-LE protocol for Location services uses SCCP as its transport layer as well.
 
SCCP also provides the capability to handle Global Titles, a mechanism by which the originator can address the destination via a "virtual address" using digits in the Called Party Address field of the SCCP layer. Accelero™ SCCP provides a comprehensive implementation of the SCCP layer as specified in BellCore Specification GR-246 (ANSI T1.112). In the ITU version there are differences like 14 bit Point Code, Called Part Address, Calling Party Address, address indicator, segmentation and some additional timers.