OUT-OF-BAND SIGNALING

1. OUT-OF-BAND SIGNALING Thought For The Week No Question Is A Bad Question!

2. INTRODUCTION • In Telephone Circuits, Signals Can Be Sent In Two • Different Ways: • In-Band • Out-of-Band • Signals Include: • Digits That You Dial • Dial Tone • Ringing • Disconnect Signals • etc.

3. In-Band Signaling

4. IN-BAND vs. OUT-OF-BAND • In-Band Signaling Signaling Made Up Of Tones Which • Pass Within The Voice Frequency Band And Are Carried • Along The Same Circuit As The Talk Path. • Out-of-Band Signaling Signaling That Is Separated From • The Channel That Is Carrying The Information, e.g. • Voice.

5. Voice Routing • For Example • Lucent 5ESS • Nortel DMS Class 5 Office Local Loop Local Loop If Endpoints In Same CO 95% Of Local Loop Circuits Are In-Band Signaling

6. Voice Routing Class 5 Office Class 5 Office Local Loop • For Example • Lucent 4ESS Local Loop Class 4 Office (W/ Tandem Switch) If Endpoints Connect To Different CO’s (One-Hop) Interoffice Signaling Via In-Band Signaling

7. Out-Of-Band-Band Signaling

8. COMMON CHANNEL SIGNALING (CCS) • Common Channel Signaling Is The Most Prominent Out- • of-Band Signaling System. • Common Channel Interoffice Signaling A Way Of Transmitting All Signaling Information For A Group Of Trunks In A Separate Channel. Class 5 CO Class 5 CO Voice Path Separate Signaling Network

9. COMMON CHANNEL SIGNALING (SS7) • Common Channel Signaling System No. 7(i.e. • SS7) • A Global Standard For Telecommunications Defined • By The International Telecommunication Union (ITU) • Telecommunication Standards Sector (ITU-T). • The ITU Definition Of SS7 Allows For National • Variants Such As The American National Standards • Institute (ANSI)Standards Used In North America • And The European Telecommunications Standards • Institute (ETSI) Standard Used In Europe.

10. COMMON CHANNEL SIGNALING (SS7) • The SS7 Network And Protocol Are Used For: • Basic Call Setup, Management, And Tear Down. • Wireless Services Such As Personal Communications • Services (PCS), Wireless Roaming, And Mobile • Subscriber Authentication. • Local Number Portability (LNP). • Toll-free (800/888) And Toll (900) Wireline Services. • Enhanced Call Features Such As Call Forwarding, • Calling Party Name/Number Display, And Three-way • Calling • EfficientAnd Secure Worldwide Telecommunications.

11. SIGNALING SYSTEM 7 (SS7) SCP SCP STP STP STP STP Voice Path SSP SSP BRI BRI Residential PRI Residential PRI PBX PBX

12. SIGNALING SYSTEM 7 (SS7) • There Are Three Kinds Of Elements In The SS7 • Network. • SSP - A Service Switching Point (Class 5 CO • Switch). • SSPs Are Switches That Originate, Terminate, Or Tandem • Calls. • An SSP Sends Signaling Messages To Other SSPs To Setup, • Manage, And Release Voice Circuits Required To Complete • A Call.

13. SIGNALING SYSTEM 7 (SS7) - CONTINUED - • An SSP May Also Send A Query Message To A Centralized • Database (An SCP) To Determine How To Route A Call • (E.G., A Toll-free 1-800/888 Call In North America). • SCP – Service Control Point, Various Data • Bases. • An SCP Sends A Response To The Originating SSP • Containing The Routing Number(s) Associated With The • Dialed Number.

14. SIGNALING SYSTEM 7 (SS7) - CONTINUED - • An Alternate Routing Number May Be Used By The SSP If • The Primary Number Is Busy Or The Call Is Unanswered • Within A Specified Time. • Actual Call Features Vary From Network To Network And • From Service To Service.

15. FUNCTIONS OF THE SS7 NODES THE SERVCE SWITCHING POINT (SSP) • The SSP Is The Local Exchange To The Subscriber And • The Subscribers Interface To The Network. • The SSP Creates SS7 Signaling Units At The Sending SSP • And Translates Them At The Receiving SSP. • The SSP Supports Database Access Queries For 800/900 • Numbers.

16. FUNCTIONS OF THE SS7 NODES THE SERVCE TRANSFER POINT (STP) • The STP Is A Router For The SS7 Network. • It Relays Messages Through The Network, But Does Not • And Translates Them At The Receiving Originate Them. • STPs Are Installed As • A national STP. • An International STP. • A Gateway STP. • SS7 Is An International Standard, Nevertheless, There Are • “Some” Differences Between The Way That Countries • Implement SS7.

17. FUNCTIONS OF THE SS7 NODES THE SERVCE TRANSFER POINT (STP) • In The United States, SS7 Is Implemented To ANSI • Standards. • In Many Other Countries SS7 Is Implemented To ITU-T • Standards.

18. STP FUNCTIONS • In The United States, STPs Provides Conversions Between • ANSI SS7 And ITU-T SS7. • Collect And Store Traffic And Usage Statistics For OAM. • Collects Billing Information.

19. FUNCTIONS OF THE SS7 NODES THE SERVCE CONTROL POINT (SCP) • Acts As The Interface Into The Telephone Company • Databases. • Business Services Database (BSDB) • Depends On RBOC and Subscriber • Call Management Services Database • (CMSDB) • Routing Information, Some Billing • Information • Reaction To Congestion SCP

20. FUNCTIONS OF THE SS7 NODES THE SERVCE CONTROL POINT (SCP) • Acts As The Interface Into The Telephone Company • Databases. • Line Information Database (LIDB) • Calling Card, Billing, Third Party • Billing. • PINs, Custom Calling Features. • Home Location Register (HLR) • Used In Cellular Networks. • Visitor Location Register (VLR) • Used In Cellular Networks. SCP

21. SS7 LINK CLASSIFICATION • A Link Is Another Name For A Communications Channel • Or Circuit. • A Link Known Also As Access Links. Used To Connect • SSP s And SCPs To STPs. • B Link Known Also As Bridge Links. Used To Connect • Mated STP Pairs To Other Mated STP Pairs. • C Link Known Also As Cross Links. Used To Connect • STPs Together To Form Mated Pairs.

22. SS7 LINK DIVERSITY • STPs Are Deployed As Mated Pairs. • Uses A Fully Meshed Topology Which Provides 100 • Percent Redundancy. • Any Single Point Of Failure Does Not Bring Down The • System. • C Link Known Also As Cross Links. Used To Connect • STPs Together To Form Mated Pairs.

23. LOGICAL vs. PHYSICAL ADDRESSES • The Telephone User Should Not Have To Worry About • SS7 Addresses. • A Customer Should Only have To Enter A Called Party • Telephone Number – Even Non-Conventional Telephone • Numbers Such As 911, A Mobile Phone Number, Or An • 800/900 Number. • SS7 Accepts These Logical Addresses And Translates • Them To Routable Numbers. • C Link Known Also As Cross Links. Used To Connect • STPs Together To Form Mated Pairs.

24. SUMMARY • Signaling Is The Exchange Of Information Between The • Components Of A Telephony For The Purposes Of • Establishing, Monitoring, Or Releasing Phone Circuits. • The Four Main Functions Of Switch Signaling Are: • Alerting • Transmitting Address Information • Supervising • Transmitting Information.

25. SUMMARY - CONTINUED • Common Channel Signaling Was Developed By AT&T • In The 1970s After They Had Lost Significant Revenue To • Fraudulent Use Of In-Band Signaling. • Signaling System No.7 (SS7) Is A Particular Type Of CCS • Employed By Modern Telephone Networks. • SS7 Is A Standard Developed And Published By The ITU. • In SS7, Any Central Office Or Other Telecommunications • Switching Facility Is Called A Service Switching Point • (SSP). • SCPs Supply Customer Information To STPs. • STPs Act As Intermediaries For Signals Moving Between • SCPs And SSPs.

26. Five-Level PSTN Network Class 1 Regional Center Norway, IL Class 1 Regional Center Rockdale, GA Class 2 Section Center Eau Claire, WI Class 2 Section Center Greensboro, NC Toll Call Using AT&Ts Five-Level Network Class 3 Primary Center Stevens Point, WI Class 3 Primary Center Fayetteville, NC Class 4 Toll Center WaUsau, WI Class 4 Toll Center Fayetteville, NC Digital Line Card Digital Line Card Analog Line Card Analog Line Card Intra-Office Call Digital T1 Local Loop Class 5 Local Office (Wausau, WI) Analog Local Loop Class 5 Local Office (Raeford, NC) Digital T1 Local Loop Analog Local Loop Office Office Residence Residence