SS7 PROTOCOL STACK (Cont.)

 

SCCP

The Signaling Connection Control Part (SCCP) is an enhanced router that provides more complex signaling message distribution capabilities than MTP L3. While MTP L3 can only identify and distribute messages to specific points and user parts, SCCP can route messages to specific applications that reside at signaling points. Because of this capability, SCCP is the transport layer for TCAP services (e.g., wireless roaming).

 

Performing a function known as global title translation (GTT), the SCCP router can also route messages to a specific signaling point and application based on digits (e.g., numbers dialed on a phone) present in a signaling message.

 

ISUP

The Integrated Services Digital Network User Part (ISUP) is a call controller. It is responsible for providing necessary signaling for setting up and tearing down calls (e.g., telephone  conversations, faxes) that use multiple switches throughout a network. ISUP is a user of MTP L3, which sends ISUP signaling messages to this user part.

 

Note: The predecessors of ISUP were Telephone User Part (TUP) and Data User Part (DUP). ISUP incorporates all of the functionality that was offered by TUP and DUP.

 

TCAP

The Transaction Capabilities Application Part is an application protocol. It defines the signaling messages used by applications to communicate. TCAP is used for database services (e.g., 800 numbers) and a variety of TCAP data transfer capabilities.

 

TCAP allows applications that reside in an SSP to use the databases at a remote SCP. TCAP conducts remote procedure calls into the database, queries them, receives responses, and acts on those responses.

 

TCAP messages must be delivered to individual applications within the nodes to which they are addressed. As such, TCAP messages use the SCCP for transport.

• AIN: Advanced Intelligent Network is the Telcordia version of IN.
• ANSI 41: Previously known as IS-41, ANSI 41 may also be referred to as TIA/EIA 41. It is the wireless intersystem operations standard used in North America and some parts of Asia.
• GSM MAP: Global System for Mobile Communications (GSM) Mobile Application Part (MAP) is the protocol that connects wireless communication systems throughout Europe and numerous other regions of the world.
• CAP: Customized Applications for Mobile Networks Enhanced Logic (CAMEL) Application Part provides Intelligent Network capabilities for GSM.
• INAP: Intelligent Network Application Protocol is a European fixed (as opposed to mobile) wireless network standard.

 

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