Signaling System 7
Signaling System 7
1.
PSTN and TDM
2.
SS7 State of the Technology
3. Future Trends in Signaling
and Networks
Presenter: Bob Wright
Signaling System 7 Slide 1
Objectives

Define the role signaling plays in a
network

Compare the different types of
applications which use SS7

Describe at least one type of call flow
through the network using SS7,
typical of long distance calling

Describe how SS7 enables Local
Number Portability (LNP) and
cellular roaming
Presenter: Bob Wright
Signaling System 7 Slide 2
Signaling System 7

Pre-SS7
-
Per-trunk signaling (PTS)
Tones or multiple frequencies (MF)
Trunk provides monitoring and supervision
Signaling within the talk path
972-516-1234
CO A
Class 5
Office
CO B
Class 4
Office
MF Trunk
#55
CO C
Class 4
Office
MF Trunk
#1221
40%
Presenter: Bob Wright
CO D
Class 5
Office
MF Trunk
#92
973-XXX-5678
Signaling System 7 Slide 3
Presenter: Bob Wright
Signaling System 7 Slide 4
Presenter: Bob Wright
Signaling System 7 Slide 5
Signaling System 7

Making a call over the Public Switched
Telephone Network
-
-
Off hook
Dial some digits
Talk to someone anywhere in the world
Network figures out where to route the call
Set up call instantly
Tear down the call as quickly
-

Behind the scene is the backbone of signaling systems
Subsecond call setup and teardown is the goal
Evolution of signaling systems
-
-
Legacy systems
Common Channel Interoffice Signaling System
Number 7
Save time and money on the network
Introduce new features and functions in an intelligent
network
Presenter: Bob Wright
Signaling System 7 Slide 6
Signaling System 7: Purposes

Some Purposes of SS7 Network






Look ahead to determine status of called
number, reserving not occupying the talk path
1 second call set up and tear down
Integration of supervision, monitoring, billing
systems
Enable introduction of additional features and
capabilities
Access remote data bases, look up and translate
information from 800 and 900 calls
Marry various stored program-controlled
systems in the world
Presenter: Bob Wright
Signaling System 7 Slide 7
Signaling System 7: Why Out-of-Band?

Advantages over in-band signaling



Enables transport of more data at higher
speeds (56 Kbps, faster than MF)
Enables signaling at any time in the entire
duration of the call
Enables signaling to network elements to
which no direct trunk connection is
available (Advanced Intelligent Networks)
Presenter: Bob Wright
Signaling System 7 Slide 8
Signaling System 7: Architecture
Components
Signal Switching Points (SSP) are
telephone switches that generally
originate, terminate, or switch calls,
the node that provides dial tone.
SSP
Signal Transfer Points (STP) are the
packet switches of the SS7 network.
STP
Signal Control Points (SCP) are the
databases that provide information
necessary for advanced callprocessing capabilities.
Presenter: Bob Wright
SCP
Signaling System 7 Slide 9
Signaling System 7 Basic call setup
1 IAM initial address
message
STP
STP
SS7 LINKS
2 ACM address
complete message
2a. ACM
1a. IAM
3a. ANM
2b. ACM
4a. REL
3b. ANM
5b. RLC
4 REL release
message, cause
SSP
Voice Circuit
* CONVERSATION
TAKES PLACE
1b. IAM
4b. REL
SSP
Presenter: Bob Wright
5a. RLC
3 ANM answer message
(initiate billing)
5 RLC release complete
message (terminate
billing)
Signaling System 7 Slide 10
Signaling System 7: Architecture

SS7 Architecture
Basic Quad
LINKS
Presenter: Bob Wright
Signaling System 7 Slide 11
Signaling System 7

SS7 Applications

800/888/877/866/900 services

Enhancements in 800/888/877/866 call centers

911 enhancements

Class features

Calling card toll fraud prevention

Credit card approval, authentication

Software/virtual defined private networks

Call tracing

Call blocking
Presenter: Bob Wright
Signaling System 7 Slide 12
Presenter: Bob Wright
Signaling System 7 Slide 13
LNP and Signaling System 7

Three phases of LNP



Service provider portability: change telco,
keep same number
Service portability: want services not
available at local end office, change
switch, keep same telco, keep same
number
Location portability: customer moves far
away from area serviced by telco, the
further the more technical challenge to
LNP, keeping same number
Presenter: Bob Wright
Signaling System 7 Slide 14
LNP and Signaling System 7

Telecommunications Act 1996 goal:


seamless and transparent comunications for the
consumer, with a choice of providers
Major issues




Explain why the FCC is so adamant about using
LNP
explain the need to preserve our telephone
numbering systems
physical interconnection
settlements between carriers for access and cocarrier charges
Presenter: Bob Wright
Signaling System 7 Slide 15
Signaling System 7 and Key points of LNP


Demand for LNP and differences between
wireline and wireless carriers for LNP

Wireless churn and fraud

Location NP
-
Database dips (LECs, ILECs, IECs and CLECs)
-
911 issues
-
Billing issues
Describe the new components of LNP
architecture
Presenter: Bob Wright
Signaling System 7 Slide 16
LNP and Signaling System 7

Basic LNP Networks
Presenter: Bob Wright
Signaling System 7 Slide 17
LNP and Signaling System 7

Wireline E-911
ANI = automatic number ID
AMA = automatic message accounting
CAMA = Centralized AMA
PSAP = public safety answer point
ALI = automatic location information
Presenter: Bob Wright
Signaling System 7 Slide 18
LNP and Signaling System 7

Wireless E-911
PSAP = public safety answer point
GPS to locate caller
ALI = automatic location information,
and x,y coordinates
Presenter: Bob Wright
Signaling System 7 Slide 19
Presenter: Bob Wright
Signaling System 7 Slide 20
SS7 and Roaming Capabilities

Mobile registration
Presenter: Bob Wright
MSC= mobile switching center
VLR = visiting location register
HLR= home location register
Signaling System 7 Slide 21
SS7 and Roaming Capabilities

Incoming call to idle mobile set
Presenter: Bob Wright
Signaling System 7 Slide 22
Signal System 7 Summary

Summary on SS7



Call setup, administration, and tear down
have changed to an out-of-band separate
signaling system called SS7
The SS7 architecture makes it possible to
reduce costs, implement many new
applications, and integrate wired and
wireless networks
SS7 makes it possible to implement LNP
and roaming, two essential services for
subscribers and businesses
Presenter: Bob Wright
Signaling System 7 Slide 23
Signaling System 7:
Leadership Issues

LNP implementation issues

Coordination between telcos
-



Scheduling
Installation responsibilities
Customer care end to end
E911 problems, especially wireless
Roaming services




Change Management and
Mode: analog, CDMA, GSM
Applications: voice, data, video
Billing and customer care
Who is in charge?



Telcos large and small
Government
Subscriber
Presenter: Bob Wright
Signaling System 7 Slide 24
Presenter: Bob Wright
Signaling System 7 Slide 25
Future trends in networking and signaling
 The
Move Towards All IP
Networks
 Forecasted
explosion in data
traffic
 Internet
protocol (IP) networks
such as long term evolution (LTE)
 Worldwide
interoperability for
microwave access (WiMAX).
Presenter: Bob Wright
Signaling System 7 Slide 26
Future trends in networking and signaling

Economic – the need to reduce data
transport costs.

a hedge against becoming a bit pipe

reducing data transport costs, MNOs
could operate a data network
profitably.

IP-based protocols also open the door
for MNOs to deploy advanced IPbased messaging services

reduce equipment deployment
Presenter: Bob Wright
Signaling System 7 Slide 27
Future trends in networking and signaling

SS7 could help the Internet by
providing:



Improved reliability: extensive continuity
testing, access switch automatically
signals the network to reroute the calls to
another switch without affecting the
service
Better bandwidth utilization: SS7
signaling takes place out-of-band
Load balancing: more efficient use of ISP
equipment and no busy signal
Presenter: Bob Wright
Signaling System 7 Slide 28
Future trends in networking and signaling

IMS enables wireless convergence (IP
Multimedia Subsystem) based on a 3GPP
variant of SIP

Year 2002 wireless subscribers exceeded
wireline globally

IMS relies on Session Initiation Protocol
(SIP) to establish and maintain call control

SIP is becoming the signaling protocol of
choice for VoIP

SIP brings with it the advantage of presence
to multimedia, concurrent sessions
Presenter: Bob Wright
Signaling System 7 Slide 29
Future trends in networking and signaling

LTE is part of the GSM evolutionary
path beyond 3G technology, following
EDGE, UMTS, HSPA (HSDPA and
HSUPA combined) and HSPA
Evolution (HSPA+)

LTE overall objective is to provide an
extremely high performance radioaccess technology that offers full
vehicular speed mobility,

LTE assumes a full Internet Protocol
(IP) network architecture
Presenter: Bob Wright
Signaling System 7 Slide 30
Future trends in networking and signaling

Network Interconnection & Roaming
Presenter: Bob Wright
Signaling System 7 Slide 31
Future trends in networking and signaling

Application data bases and scalability

Provisioning and Database Synch
Presenter: Bob Wright
Signaling System 7 Slide 32
Future trends in networking and signaling

Mobile Tweet Publishing Architecture
Presenter: Bob Wright
Signaling System 7 Slide 33
Future trends in networking and signaling

Efficient SMS-Based Tweet Delivery

Using FDA (First Delivery Attempt)
Presenter: Bob Wright
Signaling System 7 Slide 34
CONCLUSIONS

SS7 over IP is the evolution for
signaling

Star shaped network

Clear migration path to IMS

Centralized implementation

Predictable and reliable network
performance

Architecture must be robust, able to
cover hugh network performance
requirements
Presenter: Bob Wright
Signaling System 7 Slide 35
Signaling System 7:


Research to Prepare
Thank you very much.

Careers

Software, hardware

Many aspects of network configuration

Revenue generation and protection
Robert B Wright
Presenter: Bob Wright
Signaling System 7 Slide 36