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Introduction to SCCP/TCAP

Overview

SCCP and TCAP support offers advanced routing, data transfer, and management control features. Signaling Connection Control Part (SCCP) provides both connectionless and connection-oriented network services above MTP Level 3. Transaction Capabilities Application Part (TCAP) provides transaction and remote operation capabilities to a large variety of applications distributed over the CSP and service centers in the network. The Dialogic SCCP/TCAP implementation supports the following connectionless services:

• Specialized Routing

• Data Transfer

• Management Control

The SCCP layer and TCAP layer services are directly accessible through the SCCP and TCAP primitives. The option of using SCCP services only or using both SCCP and TCAP services is configurable for each subsystem. This allows users to choose the appropriate protocol interface for customized applications.

SCCP

Together SCCP and MTP are used as the network layer for TCAP-based services. For each component of an SS7 network, SCCP provides a different service to its user which is referred to as the subsystem.

• In a Service Control Point (SCP), the sub-system of the SCCP is a database.

• For an SSP, the sub-system of the SCCP is an application software package.

• For a Signal Transfer Point (STP), the SCCP also provides Global Title Translation.

TCAP

TCAP enables the deployment of advanced intelligent network services by supporting non-circuit related information exchange between signaling points using the SCCP connectionless service. TCAP provides the framework to retrieve information or invoke remote operations.

TCAP offers the means for end users in the SS7 network to query another end office and acts as the software interface between an SS7 office and database services in order to obtain data from the SS7 network.

Figure 6-1 Mapping SS7 stack to OSI layers

SCCP/TCAP in the CSP Architecture

SCCP and TCAP provide the services to the host by a set of SCCP primitives and a set of TCAP primitives which are carried in the PPL Event Request and PPL Event Indication API messages.

ITU and ASNI/Telecordia Standards - Versions Supported

The following are the standards versions that the SCCP/TCAP implementation supports:

• ITU Q.771-Q.774 TCAP 1997

• ANSI T1.114 TCAP 2000 and Telecordia GR-246 issue 7

• ANSI T1.112 SCCP 2000 and Telecordia GR-246 issue 7

See Transaction Capability Application Part.
SCCP. The signaling connection and control part of the SS7 signaling protocol. For example, performs Global Title Translations (GTT), Subsystem Management.
See Message Transfer Part.
TCAP. The transaction capabilities application part of the SS7 protocol. It is the top layer of the SS7 stack, equivalent to Layer 7 of the OSI model.
See Signaling System Number Seven.
SubSystem Prohibited. See also Service Switching Point.
STP. A node in the telephony network that normally does not handle voice. It acts as a message router, transferring signaling messages between switches.
Open System Interconnection model
See Programmable Protocol Language.
A condition that, when met, drives a state machine from one state to another. A condition that drives a Component out of its current state by invoking an associated primitive.
International Telecommunications Union (UN)
Functional Description of TCAP
ITU-TSS Publication on TCAP Procedures
American National Standards Institute. ANSI administers and coordinates the U.S. voluntary standardization and conformity assessment system for the
telecommunications industry. More details on these standards may be
viewed at www.ansi.org.
Digital communications link - voice, data, and video at a 1.544 Mbps rate (24 64 Kbps channels)
ANSI Publication on SCCP