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SS7 Tutorial |
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Overview |
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| 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: |
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- basic call setup, management, and tear down
- wireless services such as personal communications services
(PCS), wireless roaming, and mobile subscriber authentication
- local number portability (LNP)
- toll-free (800/888) and toll (900) wireline services
- enhanced call features such as call forwarding, calling
party name/number display, and three-way calling
- efficient and secure worldwide telecommunications
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| Signaling Links |
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| SS7 messages are exchanged between
network elements over 56 or 64 kilobit per second (kbps) bidirectional
channels called signaling links. Signaling occurs out-of-band
on dedicated channels rather than in-band on voice channels.
Compared to in-band signaling, out-of-band signaling provides: |
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- faster call setup times (compared to in-band signaling
using multi-frequency (MF) signaling tones)
- more efficient use of voice circuits
- support for Intelligent Network (IN) services which require
signaling to network elements without voice trunks (e.g.,
database systems)
- improved control over fraudulent network usage
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| Source: |
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| Telecom
Education and Tutorials |
| Your One Stop Resource for Telecommunications
Educational Opportunities URL: http://telecom.about.com/library/bl_education.htm
(About Telecom) |
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