What is SS7?
Common Channel Signaling System No. 7 (i.e., SS7 or C7) is a global standard for
telecommunications defined by the International Telecommunication Union (ITU)
Telecommunication Standardization Sector (ITU-T). The standard defines the procedures and protocol by which network elements in the public switched telephone network (PSTN) exchange information over a digital signaling network to effect wireless (cellular) and wireline call setup, routing and control. The ITU definition of SS7 allows for national variants such as the American National Standards Institute (ANSI) and Bell Communications Research (Telcordia Technologies) standards used in North America and the European Telecommunications Standards Institute (ETSI) standard used in Europe.
The SS7 network and protocol are used for:
1.) basic call setup, management, and tear down
2.) wireless services such as personal communications services (PCS), wireless roaming, and mobile subscriber authentication
3.) local number portability (LNP)
4.) toll-free (800/888) and toll (900) wireline services
5.) enhanced call features such as call forwarding, calling party name/number display, and three-way calling
6.) efficient and secure worldwide telecommunications
Why SS7oIP?
The main idea of transporting SS7 over IP is that SS7 user protocols residing on various nodes need to maintain their existing peer-to-peer relationship, when they communicate. SS7 user information maintained in its original form can be transported over IP and facilitate this communication between nodes on SS7 network, IP network or both. The goal of this project was to provide a reliable transport of SS7 user information over IP network. With the user adaptation of MTP3 layer, the functional objective and the required behavior of signaling can be achieved in IP network. SS7 over IP is a promising concept, which will bridge the gap between the traditional SCN and IP.
Following are the advantages of SS7 over IP:
1.) An SS7/IP protocol interests both carriers and telephony backbone providers for two primary reasons:
its relative simplicity
its ability to bridge the old with the new
2.) SS7/IP is easier to implement than the complex, SS7 protocol, especially for carriers with experience in transporting other software layers over IP. For companies with IP legacies, SS7/IP development and adoption provides the quickest path to signaling for VoIP applications.
3.) An SS7/IP standard also is attractive because it promises to be a practical solution for connecting the SS7 and IP worlds. Most end users would be happy to have a single system to unify voice, data and video if it is affordable, easy to use, and provides no drawbacks, rather than using two independent phone and Internet systems. Most carriers and their vendors would be thrilled to make money using a single unified infrastructure.
4.) SS7 over IP sets the standards for efficient interoperability. There is no requirement for a single vendor solution.
5.) Reliability consistent with the existing SS7 networks viz -a - viz:
Solid transport foundation
Flexibility to support multiple networks and applications
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