Signaling System #7
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Joined: Feb 2011
02-03-2011, 10:55 AM
KAMAL RAJ SINGH
MPC PPT.pptx (Size: 81.29 KB / Downloads: 66)
Types of Signaling
Signaling in Telecommunications Network
Channel Associated Signaling (CAS)
Common Channel Signaling (CCS)
Channel Associated Signaling (CAS) :-
Used for In-Band Signaling .
Signaling is transmitted in the same frequency band as used by voice.
Common Channel Signaling (CCS):-
Out of Band signaling
Employs separate, dedicated path for signaling.
Voice trunks are used only when a connection is established, not before.
Faster Call Setup.
Signaling System Number (SS7) is a form of Common Channel Signaling
SS7 protocol used by the telephone companies for interoffice signaling
SS7 Protocol Architecture
The SS7 User Part: Provides call control and management function and call set-up capabilities to the network.These higher layers in the SS7 utilize the transport facility provided by MTP(Message transfer part) and SCCP (signaling connection control part)
ISDN User Part (ISUP)
Used to set up telephone calls in PSTN
When a telephone call is set up from one subscriber to another, many telephone exchanges will be involved, possibly across international boundaries.
To allow a call to be set up correctly, where ISUP is supported, a switch will signal call-related information to the next switch in the network using ISUP messages.
The telephone exchanges are connected via trunks which transport the speech from the calls.
These trunks are divided into 64 Kbit/s timeslots, and one timeslot can carry exactly one call.
Each timeslot between two switches is uniquely identified by a Circuit Identification Code (CIC) that is included in the ISUP messages.
The exchange uses this information along with the received signaling information (especially the Called Party Number) to determine which inbound CICs and outbound CICs should be connected together to provide an end to end speech path.
Transaction Capabilities Applications Part (TCAP)
Its primary purpose is to facilitate multiple concurrent dialogs between the same sub-systems on the same machines, using Transaction IDs to differentiate these, similar to the way TCP ports facilitate multiplexing connections between the same IP addresses on the Internet .
TCAP messages are sent over the wire between machines.
Operation Maintenance and Administration part (OMAP)
OMAP is a TCAP application for network management i.e. monitoring ,coordination and control function for trouble free communication
Signaling Traffic in SS7
Maximum signaling traffic in a network is generated by Call set-ups, inter-MSC handoffs and location update
Setting up of a call requires exchange of information about the location of calling subscriber and information about the location about the called subscriber
Either one or both subscriber can be mobile
When any of mobile subscriber switches MSCs under a handoff condition , it adds to the amount of information exchanged
Location update records are updated in the network whenever a subscriber moves to a new location
Signaling Load For a Call setup and Handoffs in GSM
Signaling load for location updating in GSM
This kind of service is also known as CLASS
This is a group of switch-controlled services that provide its users with certain call management capabilities
Services provided are Call return, Call forwarding, Repeat dialing, Call block ,Call tracing and Caller ID
These services were introduced by Bell System to provide toll-free access to the calling party to the services and database which is offered by the private parties
The costs associated with the processing of calls is paid by the service subscriber
The service is offered under two plans known as the 800-NXX plan and the 800 database plan
In 800-NXX plan the first six digits of an 800 call are used to select the interexchange carrier (IXC)
In the 800 data database plan , the call is looked up in a database to determine the appropriate carrier and routing information
Alternating Billing Services And Line Information Database (ADB/LIDB)
These services use the CCS network to enable the calling party to bill a call to a personal number (third party number, calling card , or collect etc.) from any number
Joined: Apr 2012
26-04-2012, 04:04 PM
Signaling System #7
49332924-E-Book-SS7-Tutorial.pdf (Size: 903.42 KB / Downloads: 29)
Menu selections are indicated in bold with the main menu choice divided from
the sub-menu choices by ->. Icons and buttons, that you need to click on, field
names in dialogs, and text you have to type in the dialog fields are also
indicated in bold.
Signaling links are logically organized according to their use in the SS7 network.
There is no difference between the various links, only in the way the links are
utilized during message transfer and the way network management interacts with
A - Access links between end points (e.g. an SCP or SSP) to an STP
B - bridge links connect an STP to another STP. Typically, a quad of B links
interconnect peer STPs (e.g. STPs from one network to the STPs of another
C - Cross links connect STPs performing identical functions into a mated pair.
D - Diagonal links connect mated pairs of STPs at different hierarchical level.
E - Extended links connect SSps to a remote STP pair. E links privide an alternate
signaling path if an SSP’s home STP cannot be reached via an A link.
DTE & DCE Configuration
The picture of the jumpers settings for DCE and DTE is shown in the slide.
The V.35 Configurable Pods allow you to configure the connectors to match
Each port on the pod is configurable to suit the equipment it is connected to by
setting jumpers inside the V.35 box.
The slide illustrates the position of the jumpers for DTE and DCE
Joined: Apr 2012
21-08-2012, 04:24 PM
SIGNALING SYSTEM NUMBER 7
SIGNALING SYSTEM.ppt (Size: 1.27 MB / Downloads: 19)
Introduction to Signaling System
Transmission: A way by which the information is transported in cost efficient way from
Source to Destination Point over a physical line.
Switching: A process by which an inlet has to be connected through a correct outlet.
Thus we have two type of signaling systems.
UNI Signaling System.
NNI Signaling System.
UNI Signaling System: The most common form of UNI Signaling is “ISDN-Signaling”
or “D-Channel” Signaling. For broadband purposes, we use ATM switching in lower layers.
b) NNI Signaling System: The most common form of NNI Signaling is “Common Channel
Signaling System No. 7 (CCS#7) or Signaling System Number 7 (SS7)”
Signaling System Number 7 is a global standard defined by ITU-T which defines the procedures
by which the information is exchanged between the switches in order to perform functions like
call set up, call management and tear down.
Thus signaling messages are exchanged between the switches over 56 or 64 kbps bi-directional
link called signaling link.
Signaling Network Components
All the Nodes in the SS7 network are called Signaling Points. Following are the signaling points
used in a telecommunication network.
Signaling End Point (SEP): It is a node in a telecommunication network to which subscriber
lines are attached. It is a source or the sink of signaling traffic.
b) Signaling Transfer Point (STP): All the CCS messages travel from one SEP to another by the
services of a STP. The STP switches the messages as received from various SEPs through the
network to their appropriate destination i.e. to the destination SEP.
Architecture of CCS#7 Network
In order to obtain this flexibility, a modular and layered structure is required. The fundamental
principle of CCS#7 is the divisions of functions into a common “Message Transfer Part (MTP)”
on one hand and a separate “User part” on other hand. The same MTP supports as transport
system for different User Parts. We can represent this functionality in a layered manner on
Telecommunication network is changing day by day. In order to cope with this changing
environment, a very flexible signaling system is required, which can perform signaling
functions for all kinds of telecom applications, already existing, or even future applications
yet o be defined.