Signaling System No. 7 is a set of telephony signaling protocols developed in 1975, which is used to set up and tear down telephone calls in most parts of the world-wide public switched telephone network. What is Signaling?Common Channel Signaling Modes?What is SS7?

2. Group Member
ID Name
172-19-1998 Abdullahi Shire Ali
172-19-2000
173-19-2009
Mohamud abdi Osman
Abdullahi Ismacil
Presented
Tasnuva Ali
Assistance Pro
Dept. OF ETE
Daffodil International
University
153-19-1824 Tahmid Rahman
Khan

3. What is Signaling
• Signaling refers to the exchange of information between network
elements
• 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.

4. Common Channel Signaling Modes
Signaling
Modes
Associated
Quasi-
associated
Non-
associated

5. Cont.….
• Associated Signaling is uses one dedicated path between switches as
the signaling link
• Non-Associated Signaling is uses separate logical paths and multiple
nodes
• Quasi-Associated Signaling—Uses a minimal
number of nodes (preferred for SS7, causes
less delay).

6. What is SS7?
• Signaling System 7 (SS7) is an international telecommunications
standard that defines how network elements in a public switched
telephone network (PSTN) exchange information over a digital
signaling network.
• Nodes in an SS7 network are called signaling points.

7. Why we use SS7
Setting up and managing the connection for a call
Tearing down the connection when the call is complete
Billing
Managing call forwarding, calling party name and number display,
three-way calling, and other Intelligent Network (IN) services
Toll-free (800 and 888) and toll (900) calls
Wireless as well as wireline call service including mobile telephone
subscriber authentication, personal communication service (PCS), and
roaming

8. What is out-of-band signaling
• SS7 uses out-of-band signaling, which means that signaling (control)
information travels on a separate, dedicated 56 or 64 Kbps channel
rather than within the same channel as the telephone call.
• Historically, the signaling for a telephone call has used the same voice
circuit that the telephone call traveled on (this is known as in band
signaling).
• Using SS7, telephone calls can be set up more efficiently and special
services such as call forwarding and wireless roaming service are
easier to add and manage.

9. Why Out-of-band signaling use
• Out-of-band signaling has several advantages that make it more
desirable than traditional in-band signaling
• It allows for the transport of more data at higher speeds (56 kbps can
carry data much faster than MF out pulsing).
• It allows for signaling at any time in the entire duration of the call, not
only at the beginning.
• It enables signaling to network elements to which there is no direct
trunk connection.

10. SS7 Network Elements
• There are three kinds of network points signaling points
I. Service Switching Points (SSPs)
II. Signal Transfer Points (STPs)
III. Service Control Points (SCPs)

11. Cont.…….

12. Cont..
• SSPs are telephone switches (end offices or tandems) equipped with
SS7−capable software and terminating signaling links. They generally
originate, terminate, or switch calls.
• STPs are the packet switches of the SS7 network. They receive and
route incoming signaling messages towards the proper destination.
They also perform specialized routing functions
• SCPs are databases that provide information necessary for advanced
call-processing capabilities

13. SS7 Links Interface

14. Cont.…
• A link (access)
-Connects signaling end point (SCP or SSP) to STP
• B link (bridge)
-Connects an STP to another STP(STPs from a network connect to STPs
of another network)
• C link (cross)
-Connects STPs performing identical functions, forming a mated pair
(for greater reliability)

15. Cont..
• D link (diagonal)
-Connects a secondary (local or regional) STP pair to a primary
(internetwork gateway) STP pair in a quad-link configuration; the
distinction between B and D links is arbitrary
• E link (extended)
-Connects an SSP to an alternate STP
• F link (fully associated)
-Connects two signaling end points (SSPs and SCPs) in the same local
network

16. Cont.…

17. Layers of the SS7 Protocols
MTP1
MTP2
MTP3
ISUP
SCCP
Physical
Data Link
Network
Presentation
Transport
Session
Application
TCAP
MAP/INAP
I. Massege Transfer part 1
II. Massege Transfer part 2
III. Massege Transfer part 3
IV. Signaling Connection Control Part
V. Transaction Capabilities Application Part
VI. Mobile Application Part
VII. IN Application part

18. MTP1(Physical Layer)
• MTP1 is equivalent to the physical layer of the OSI model
• MTP1 defines the physical and electrical characteristics of the
signaling link.
• The physical interfaces defined for SS7 include E-1 (2048kb/s;
3264kb/s channels), DS-1(1544kb/s; 24 64kb/s channels),
V.35(64kb/s), DS-0(64kb/s) and DS0A(56kb/s)
• MTP1
• Physical layer
• DS-0 channel (56k or 64bit

19. MTP2(Physical Layer)
• MTP2 ensures reliable end-to-end transmission of a message across a
signaling link that directly connects 2 nodes.
• Implements flow control, message sequence validation, error checking
and error recovery.
• MTP2
• Data Link Layer
• Ensures reliable transmission
• Error checking, flow control, and sequence checking

20. MTP3(Physical Layer)
• MTP3 provides message routing between signaling points in the ss7
network
• MPT3 reroutes traffic away from failed lins and signaling points and
controls traffics when congestion occurs.
• MTP3
• Network Link Layer
• Ensures message delivery in the network
• Addressing, routing, and congestion control

21. Cont...
• ISUP
• Application Layer
• Protocol that establishes calls between 2 end points
• Call setup, call information, and call tear down