Common channel signalling (CCS) and channel associated signalling (CAS) are the signalling techniques in telecommunication.

1. Government Engineering
College, Bharuch
Telecommunication Switching
Systems And Network presentation

2. Signaling TechniquesSignaling Techniques
Basics of CCSBasics of CCS
Prepared by :
Xyz
6th
Sem (E.C-A)

3. Signaling Definition
It is the dialog language for the
communication between various parts
of the telecom network.

4. Working area
•Subscriber signaling: Between sub. & switch
•inter-office: Control the setup and release of call
Signaling function
Monitoring signals: Monitor the changes of call states or conditions
in the lines
•Selection signals ： Routing information
•Operation signals: Management and maintenance of telecom
networks
Signaling Classification

5. Transmitting path
1.Channel Associated Signaling
2.Common Channel Signaling

6. Common Channel Signaling (CCS)
In telephony, Common Channel Signaling (CCS), is the
transmission of signaling information (control information) on a
separate channel from the data, and, more specifically, where
that signaling channel controls multiple data channels.
Channel Associated Signaling (CAS)
Channel Associated Signaling (CAS), also known as per-trunk
signaling (PTS), is a form of digital communication signaling.
As with most telecommunication signaling methods, it uses
routing information to direct the payload of voice or data to its
destination. With CAS signaling, this routing information is
encoded and transmitted in the same channel as the payload
itself.

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Common Channel Signaling System

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Channel Associated Signaling

9. Advantages of CCS
Compared with Channel Associated Signaling,
Common Channel Signaling has many important
advantages
• Information can be switched between processors
much faster than in channel-associated signaling.
• With a huge signal capacity, it can hold dozens or
even hundreds of different kinds of signals, thus
providing more new services.

10. • With a great flexibility, it can provide more new
services simply by modifying software to increase
signals.
• Line signaling device is not needed any more at
any trunk station, which shall greatly reduce
investment costs.
• Since line signaling is no longer needed, trunk
devices can be used both in calls from A to B, and
in calls from B to A.
• In such bi-directional working modes, even less
circuits are required than when trunk circuits are
respectively used in single call directions.

11. • When a call is being set up, signals related to this call can
be sent. In this way, the subscriber can change the already
setup connections. For example, the subscriber can
transfer one call to another place, or request a third party
to join the present connections.
• Signals can be switched between processors so as to be
used for maintenance or network management.
• Signaling can provide powerful support for ISDN, IN, TMN
(telecommunication management Network) and cellular
mobile communication systems, as this signaling is their
basis.

12. Disadvantages of CCS
• The error rate of the common channel signaling
system must be very low.
• Its reliability must be much higher than the
channel associated signaling system. This is
because once the data link fails, all related calls
between the two related switches shall be
affected.

13. Common Channel Signaling Network
The CCS network consists of the following parts
• Signaling point (SP)
It refers to the node in the signaling system
that provides Common Channel Signaling. SP can
also be divided into source points
– OPC (Originating Point Code)
The SP that generate signaling messages
– DPC (Destination Point Code)
The SP that receives signaling point code.

14. Thank You