ss7a - Signaling System 7 (SS7) Definition Signaling System...

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Web ProForum Tutorials Copyright © The International Engineering Consortium 1/29 Signaling System 7 (SS7) Definition Signaling System 7 (SS7) is an architecture for performing out-of-band signaling in support of the call-establishment, billing, routing, and information-exchange functions of the public switched telephone network (PSTN). It identifies functions to be performed by a signaling-system network and a protocol to enable their performance. Topics 1. What Is Signaling? 2. What Is Out-of-Band Signaling? 3. Signaling Network Architechture 4. The North American Signaling Architecture 5. Basic Signaling Architecture 6. SS7 Link Types 7. Basic Call Setup Example 8. Database Query Example 9. Layers of the SS7 Protocol 10. What Goes Over the Signaling Link 11. Addressing in the SS7 Network 12. Signal Unit Structure 13. What Are the Functions of the Different Signaling Units? 14. Message Signal Unit Structure Self-Test Correct Answers Glossary
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Web ProForum Tutorials Copyright © The International Engineering Consortium 2/29 1. What Is Signaling? Signaling refers to the exchange of information between call components required to provide and maintain service. As users of the PSTN, we exchange signaling with network elements all the time. Examples of signaling between a telephone user and the telephone network include: dialing digits, providing dial tone, accessing a voice mailbox, sending a call-waiting tone, dialing *66 (to retry a busy number), etc. SS7 is a means by which elements of the telephone network exchange information. Information is conveyed in the form of messages. SS7 messages can convey information such as: I’m forwarding to you a call placed from 212-555-1234 to 718-555- 5678. Look for it on trunk 067. Someone just dialed 800-555-1212. Where do I route the call? The called subscriber for the call on trunk 11 is busy. Release the call and play a busy tone. The route to XXX is congested. Please don’t send any messages to XXX unless they are of priority 2 or higher. I’m taking trunk 143 out of service for maintenance. SS7 is characterized by high-speed packet data and out-of-band signaling . 2. What Is Out-of-Band Signaling? Out-of-band signaling is signaling that does not take place over the same path as the conversation. We are used to thinking of signaling as being in-band. We hear dial tone, dial digits, and hear ringing over the same channel on the same pair of wires. When the call completes, we talk over the same path that was used for the signaling. Traditional telephony used to work in this way as well. The signals to set up a call between one switch and another always took place over the same trunk that would eventually carry the call. Signaling took the form of a series of multifrequency (MF) tones, much like touch tone dialing between switches. Out-of-band signaling establishes a separate digital channel for the exchange of
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This note was uploaded on 08/08/2011 for the course CS 310 taught by Professor Aartisingh during the Spring '11 term at National Institute of Technology, Calicut.

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ss7a - Signaling System 7 (SS7) Definition Signaling System...

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