1 cns 479r voice over ip signaling system 7 gary d. brown, guest lecturer
TRANSCRIPT
![Page 1: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/1.jpg)
1
CNS 479R Voice Over IP
Signaling System 7Gary D. Brown, Guest Lecturer
![Page 2: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/2.jpg)
2
Signaling System 7 (SS7)
• Introduction
• SS7 Network Architecture
• SS7 Protocols
• SS7 Call Signaling
• VoIP Issues
• NG9-1-1 Architecture
![Page 3: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/3.jpg)
3
Introduction
• Public Switched Telephone Network (PSTN)– Time-Division Multiplexed (TDM) Technology– Wire-line Network– Wireless Network– SS7 Network
• Business Models
• Applications
![Page 4: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/4.jpg)
4
Wire-line Network
• Terminals– Telephones– Facsimile machines– Modems– Video Conferencing Systems– 143 Million (2004) in the United States– 1 Billion+ terminals worldwide
![Page 5: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/5.jpg)
5
Wire-line Network
• Switches– Central Office (End Office) Switches
• Connect terminals to PSTN (lines)• Interconnect with tandem switches (trunks)
– 142 Million (2004) in the United States
• 17,932 CO switches (2004) in the United States
– Tandem Switches• Interconnect CO and tandem switches• Form PSTN “back-bone” network
– National tandems– International tandems (same network between countries)– International Gateway tandems (different network types)
![Page 6: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/6.jpg)
6
Wire-line Network Architecture
Lines
Trunks
International Network
National Network
National Tandem
International Gateway Tandem
Central Office
![Page 7: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/7.jpg)
7
Wireless Network
• Wireless Terminals– Mobile Phones– Laptop Computers– Personal Digital Assistants (PDA)– 213 Million (2005) in the United States– 1 Billion+ worldwide
![Page 8: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/8.jpg)
8
Wireless Network
• Base Station Controllers (BSC)– Control multiple Antennas (cell towers)– TDM-to-radio conversion and frequency control– Limited switching capability
• Mobile Switching Centers (MSC)– Wireless equivalent of “Central Office” switch– Control multiple Base Station Controllers– Interconnect with tandem switches– 1,000+ in the United States
![Page 9: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/9.jpg)
9
Wireless Network Architecture
MSC
International Network
National Network
Central Office
National Tandem
International Gateway Tandem
Radio
Trunks
Lines
BSC
![Page 10: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/10.jpg)
10
SS7 Network
• Created in late 1970s—deployed 1980s– About same time as IP network
• Purpose-built for PSTN– Specifically designed for voice calls and
services
• Interconnects PSTN switches and networks– Wire-line CO and tandem switches– Wireless MSC– National/International networks
![Page 11: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/11.jpg)
11
SS7 Network Interconnection
MSC
International Network
National Network
Central Office
National Tandem
International Gateway Tandem
Radio
Trunks
Lines
BSC
SS7
![Page 12: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/12.jpg)
12
SS7 Network
• Interconnects all wire-line and wireless networks
• Interconnects with VoIP networks via SS7/VoIP signaling gateways
• Very important infrastructure network– AT&T’s “Black Monday” in 1980s
• Entire 1-800 network failed• Congressional hearings held to determine blame!
![Page 13: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/13.jpg)
13
PSTN Business Models
• Carriers or Service Providers– Local Exchange Carriers (LEC)
• Incumbent LEC (ILEC) (e.g. Qwest Communications)
• Competitive LEC (CLEC) (e.g. Veracity)
• Local Telephone Companies
– Inter-exchange Carriers (IXC)• Long Distance Telephone Companies (e.g. AT&T, Sprint)
• Switch-less Resellers
– Mobile Network Operators (MNO) (e.g. Sprint PCS, T-Mobile)
• Mobile Virtual Network Operators (MVNO) (e.g. TracPhone)
• Geographic Area/Coverage
• Interconnected via SS7 Network
![Page 14: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/14.jpg)
14
Applications
• POTS (Plain Old Telephone Service)
• 800 toll-free service
• 900 premium service
• Directory Assistance
• Operator Assistance
• Conferencing Service
• Local Number Portability (LNP)– Wireless Local Number Portability (WLNP)
• Line Information Database (LIDB)– Billed Number Screening (BNS)
![Page 15: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/15.jpg)
15
SS7 Network Architecture
• Network Elements (components)
• Redundancy
• Addressing
• Interconnections
![Page 16: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/16.jpg)
16
SS7 Network Elements
• Circuits– TDM-based– Voice Circuits– Signaling Circuits
Type T-Carrier (NA/Japan) Capacity
DS0 64 Kbps 1
T1 1.544 Mbps 24
T3 44.736 Mbps 672
Type Optical Carrier
OC-1 51.84 Mbps
OC-3 155.52 Mbps
OC-12 622.08 Mbps
OC-48 2.488 Gbps
OC-192 9.953 Gbps
Type E-Carrier (RoW) Capacity
DS0 64 Kbps 1
E1 2.048 Mbps 30/31
E3 34.368 Mbps 480/496
![Page 17: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/17.jpg)
17
• Nodes– Service Switching Point (SSP)
• Central Office Switches (CO)• Mobile Switching Centers (MSC)• [Access] Tandem Switches (AT)• Controls calls• Asks for services
– Signal Transfer Point (STP)• Forwards SS7 Messages
– Service Control Point (SCP)• Provides services
SS7 Network Elements
![Page 18: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/18.jpg)
18
SS7 Network Elements
SS7 Network
SSP
STP
SCP
IP Network
LAN
Router
Server
≡
Service Switching Point
Signaling Transfer Point
Service Control Point
Switches between computers
Forwards packets
Provides services
![Page 19: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/19.jpg)
19
SS7 Network Elements
CO Switch
Tandem Switch
MSC Switch
STPHome Location Register (HLR)
Voice Circuits Voice Circuits
SS7 Messages SS7 MessagesSS7 Messages
SS7 Messages
Global Title Translation
(GTT)
SS7 Messages
![Page 20: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/20.jpg)
20
SS7 Signaling Links
• Physical Connection– DS0 channel in T1/E1 circuit (very common)
– V.35 modem (older technology)
– IP network (newer technology)
• Bandwidth– 56Kbps (robbed-bit T1)– 64Kbps (clear channel T1 and E1)
• Link Sets– Dual data links for Redundancy
![Page 21: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/21.jpg)
21
STPPair
STPPair
SS7 Signaling Links/Redundancy
• A-links – links between STP A-links – links between STP and SSP or SCP endpointsand SSP or SCP endpoints
• B-links – bridge links between B-links – bridge links between mated pairs of STPsmated pairs of STPs
• C-links – cross link between C-links – cross link between STPs within STP pairSTPs within STP pair
• D-links – diagonal links D-links – diagonal links between mated STP pairs in between mated STP pairs in different networksdifferent networks
• E-links – extended links E-links – extended links between SSP and alternate between SSP and alternate STPSTP
• F-links – links between SSPsF-links – links between SSPs
SCP SCP
SSPSSPVoice Circuits
![Page 22: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/22.jpg)
22
SS7 Addressing
• Point Codes and Circuit Identification Codes– ANSI
• 24-bit point code (16,777,216 nodes)• 14-bit circuit identification code (16,384 circuits)• North America, Japan, China
– ITU• 14-bit point code (16,384 nodes)• 12-bit circuit identification code (4,096 circuits)• Rest of World (RoW)
![Page 23: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/23.jpg)
23
SS7 Addressing
• Origination Point Code (OPC)– Sender of SS7 message
• Destination Point Code (DPC)– Receiver of SS7 message
• Circuit Identification Code (CIC)– Identifies physical circuit between SSPs– Circuits have common numbering between SSPs
• SS7 Call Signaling Messages contain OPC, DPC and CIC
![Page 24: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/24.jpg)
24
SS7 Interconnections
• SSP-to-SSP (switch-to-switch)– F-link used to directly interconnect switches– Uses one DS0 channel of T1 circuits between
switches– Sometimes used in North America
SSPSSPVoice Circuits
SS7 F-link
![Page 25: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/25.jpg)
25
SS7 Interconnections
• SSP-to-STP (switch-to-SS7 network)– Uses A-link to interconnect SSP and STP– Uses one DS0 channel of T1 or E1 circuit—no
channels used for voice– Commonly used throughout the world—required in
Europe
SSPSSPVoice Circuits
SS7 A-links
SSP
SSPSTP STP
![Page 26: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/26.jpg)
26
SS7 Interconnections
• SS7 Signaling Transport Companies– AT&T Wholesale
• Was SNET (Southern New England Telephone)– Connecticutt ILEC
• ISUP Gateway Service• LNP Gateway Service• 8XX Gateway Service• SOA (Service Order Administration) Service
Bureau– Ports subscribers to other carriers (LNP)
• CLASS (Custom Local Area Signaling Services) gateway
![Page 27: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/27.jpg)
27
SS7 Interconnections
• SS7 Signaling Transport Companies– VeriSign
• Illuminet (purchased in 2001)• 15 STP Pairs• Largest independent U.S. SS7 transport network• Interconnects with nearly all carriers in North,
Central and South America
– IXCs (e.g. Sprint LD, MCI)– LECs (Qwest, Verizon)
![Page 28: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/28.jpg)
28
Wireless 1-800 Call
CO Switch
Tandem Switch
MSC Switch
STPHome Location Register (HLR)
Global Title Translation
(GTT)
Mobile phone dials 1-800 number. MSC verifies phone is a customer.
![Page 29: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/29.jpg)
29
Wireless 1-800 Call
CO Switch
Tandem Switch
MSC Switch
STPHome Location Register (HLR)
Global Title Translation
(GTT)
MSC asks for Global Title Translation of 1-800 number, which gives actual destination.
![Page 30: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/30.jpg)
30
Wireless 1-800 Call
CO Switch
Tandem Switch
MSC Switch
STPHome Location Register (HLR)
Global Title Translation
(GTT)
MSC switch passes call information to and requests circuit from Tandem switch.
![Page 31: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/31.jpg)
31
Wireless 1-800 Call
CO Switch
Tandem Switch
MSC Switch
STPHome Location Register (HLR)
Global Title Translation
(GTT)
Tandem switch passes call information to and requests circuit of CO switch.
![Page 32: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/32.jpg)
32
Wireless 1-800 Call
CO Switch
Tandem Switch
MSC Switch
STPHome Location Register (HLR)
Global Title Translation
(GTT)
Circuit path completed and called party alerted.Answer supervision returned when called party answers and billing starts.
![Page 33: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/33.jpg)
33
Wireless 1-800 Call
CO Switch
Tandem Switch
MSC Switch
STPHome Location Register (HLR)
Global Title Translation
(GTT)
Call in conversation.
![Page 34: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/34.jpg)
34
Wireless 1-800 Call
CO Switch
Tandem Switch
MSC Switch
STPHome Location Register (HLR)
Global Title Translation
(GTT)
Call torn down when one party disconnects.Circuits are released and billing terminates.
![Page 35: 1 CNS 479R Voice Over IP Signaling System 7 Gary D. Brown, Guest Lecturer](https://reader030.vdocuments.net/reader030/viewer/2022032604/56649e615503460f94b5bea5/html5/thumbnails/35.jpg)
35
Signaling System 7 (SS7)
Next lecture on SS7 Protocols used between SS7 network elements