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CS 479R Telecommunications

CS 479R Telecommunications. Signaling System 7 Gary D. Brown, Guest Lecturer Lecture 3. Signaling System 7 (SS7). Introduction SS7 Network Architecture SS7 Protocols SS7 Call Signaling VoIP Issues VoIP 9-1-1. SS7 Protocols. ISUP (ISDN User Part) Call Control ISUP Messages

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CS 479R Telecommunications

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  1. CS 479R Telecommunications Signaling System 7 Gary D. Brown, Guest Lecturer Lecture 3 UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  2. Signaling System 7 (SS7) • Introduction • SS7 Network Architecture • SS7 Protocols • SS7 Call Signaling • VoIP Issues • VoIP 9-1-1 UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  3. SS7 Protocols • ISUP (ISDN User Part) Call Control • ISUP Messages • Message Parameters • ISUP Message Flows UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  4. SS7 Protocols—Architecture UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  5. SS7 Protocols—Application Protocols • ISUP ISDN User Part • Call Control Signaling (call setup and teardown) • National Variants • ITU 88 (14-bit PC/12-bit CIC) ANSI 88 (24-bit PC/14-bit CIC) • ITU 92 (14-bit PC/12-bit CIC) ANSI 92 (24-bit PC/14-bit CIC) • ITU 96 (14-bit PC/12-bit CIC) ANSI 96 (24-bit PC/14-bit CIC) • ETSI (14-bit PC/12-bit CIC) ANSI 2000 (24-bit PC/14-bit CIC) • BT ISUP (14-bit PC/12-bit CIC) (United Kingdom and former colonies) • China (24-bit PC/14-bit CIC)(ANSI MTP3/ITU ISUP) • Telefónica (14-bit PC/12-bit CIC) (Spain, Portugal, South America) • ITU-T Q.761-Q.769 UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  6. SS7 Protocols—Call Control • E.164 Numbering and Number/Dialing Plans • Privacy Considerations • ISUP Message Parameters • Common Message Parameters • Scenarios for Optional Parameters • Q.763 – ISUP Formats and Codes UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  7. SS7 Protocols—E.164 Numbering • E.164 Numbers • ITU-T Standard—governs format of country codes and national numbers • Maximum 15 digits (country code + national number) • Maximum 3-digit Country Code (CC) • 1st digit is World Zone (1-9) • 2nd digit for 2-digit country codes • 3rd digit for 3-digit country codes • Maximum 13-digit National Number (NN) • Violated by a few countries (Germany, China) • Numbers reclaimed and split based on political exigencies • Examples: East Germany, Soviet Union and Yugoslavia UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  8. SS7 Protocols—E.164 Numbering • World Zones • 1 North America (US, Canada, Caribbean) • 2 Africa • 3/4 Europe • 5 Central/South America • 6 Pacific Ocean/Australia • 7 Russia + some former colonies • 8 Asia • 9 Middle East UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  9. SS7 Protocols—E.164 Numbering • Variable-length “exclusionary” Country Code • Example: • 1 – North America • No “10”-”19” country codes • No “100”-”199” country codes • 49 – Germany • No “490”-”499” country codes • Many countries’ City Codes follow same “exclusionary” scheme • Very difficult to add new national numbers in a small geographic area without resorting to longer numbers UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  10. SS7 Protocols—E.164 Numbering • National Number • National Destination Code (NDC) • Area Code • North America  3-digit area code • United Kingdom  3-digit area code • NDC • Mexico  2-digit NDC (Mexico City, Guadalajara, Monterrey) • Mexico  3-digit NDC (all other cities) • City Code • Germany  2-5 digits (large to small cities) • Subscriber Number • Remaining digits UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  11. SS7 Protocols—E.164 Numbering • Numbering Plans • Each country has its own “numbering plan” • ITU-T National Numbering Plans website • http://www.itu.int/oth/Default.aspx?parent=T0202 • Dialing Plans • Each country has its own “dialing plan” • Dialing Prefixes • Direct dial • Operator-assistance • International Direct-dial • International Operator-assistance • Live Operator • Carrier Selection UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  12. SS7 Protocols—E.164 Numbering • Local Call • Subscriber Number (North America  7/10d) • Direct-dialed Long Distance Call • North America (1+10d) • Europe (0+NN) • Live Operator • North America (0 or 00) • Europe (112) • Operator-assisted Call • North America (0+10d) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  13. SS7 Protocols—E.164 Numbering • International Direct-dial • North America (011+CC+NN) • Europe (00+CC+NN) • International Operator-assisted Call • North America (01+CC+NN) • Carrier Selection • North America (101xxxx) • Germany (12xxx) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  14. SS7 Protocols—E.164 Numbering • Service Access Codes (SAC) • North America • 311 Government Information • 411 Directory Assistance • 611 Customer Service • 711 TDD (Telephone for Deaf and Dumb) • 911 Emergency Operator • Europe • 112 Operator including Emergency • xxx Many variations based on country (fire, police, avalanche) • United Kingdom • 112 Operator • 999 Emergency Operator (phasing out in favor of 112) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  15. SS7 Protocols—Privacy Considerations • Number Presentation (Caller ID) • Number Restriction (privacy consideration) • Calling Line Identification (CLI) • CLI Presentation (CLIP) • CLI Restriction (CLIR) • Delivered in IAM in forward direction • Connected Number (CN) • Presentation • Restriction • Delivered in ACM or ANM in backward direction • “Address Not Available” Indicator (privacy) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  16. SS7 Protocols—Privacy Considerations • Privacy Laws • Favor non-disclosure of consumer’s information • Consumer “Opt-in” requirement—opposite of U.S. • International Boundaries • Bi-lateral agreement required between carriers or service providers before can pass CLI or CN • No agreement—no CLI or CN permitted to cross country boundary REGARDLESS of CLI or CN Restriction • European Union • Severe penalties including fines and prison UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  17. SS7 Protocols—ISUP Parameters • Call Control Messages (most commonly used) • IAM Initial Address Message • SAM Subsequent Address Message • ACM Address Complete Message • ANM Answer Message • REL Release Message • RLC Release Complete Message • Required Parameters • Optional Parameters • Parameter “Direction” UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  18. SS7 Protocols—ISUP Parameters • Number Parameters • Calling Line Identification Number (CLI or CGPN) • Called Party Identification Number (CDPN) • Connected Number (CN) • Redirected Number (RN) • Number forwarded from • Original Called Party Number (OCPN) • Original called number • Charge Number (CGN) (ANSI only) • To whom to charge the call • Can be called party number UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  19. SS7 Protocols—ISUP Parameters • Numbering Plan Indicator • ISDN (E.164) • Telex, Data, Private • Nature of Address Indicator (Address format) • International (country code + national number) • National* (national number) • Subscriber (subscriber number only—should never use with VoIP) • Unknown* (may have dialing plan digits + other digits) • Additional ANSI-only Values • International and Operator Requested (ANSI) • National and Operator Requested (ANSI) • Subscriber and Operator Requested (ANSI) • Operator Requested (ANSI) • Carrier Selection (ANSI) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  20. SS7 Protocols—ISUP Parameters • Address Screening Indicator (level of trust) • Network • User Provided—Screened • User Provided—Not Screened • User Not Screened • Address • Up to 15 digits including country code (and dialing prefix digits) • Address Presentation Restriction Indicator • Presentation Restricted • Presentation Allowed • Address Not Present UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  21. SS7 Protocols—ISUP Parameters • Information Integer (II digits) • Identifies Charge Number type • POTS, payphone, hotel, prison, hospital, etc. • Important for payphone compensation, hotel billing, prison call restrictions, etc. • http://www.nanpa.com/number_resource_info/ani_ii_assignments.html • Transit Network • Carrier Selection Indicator • Presubscribed—not input by user • Presubscribed—input by user (101xxxx) • Not Presubscribed—input by user (101xxxx) • Carrier Identification Code (xxxx) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  22. SS7 Protocols—ISUP Parameters • Redirection Indicator (RI) • Rerouted (forwarded) • Diverted (e.g. voice mail) • Redirection Reason (RR) • User Busy • No Answer • Unconditional • Mobile Not Reachable • Pickup • Deflection during Alerting (e.g. voice mail on ring/no answer) • Deflection Immediate (e.g. unconditional transfer to voice mail) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  23. SS7 Protocols—ISUP Parameters Transformation of Parameters during Call Forwarding CO Switch CO Switch CO Switch CO Switch 801-555-0000 516-555-3333 212-555-1111 718-555-2222 UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  24. SS7 Protocols—ISUP Parameters • Routing Number Parameter • Used by Local Number Portability (LNP) • Usually not seen between carriers—only within single network • Jurisdiction Information Parameter (JIP) • Wireless Call Only • Mobile Phone Location (cell tower NPA-NXX) • Use to compute billing time-of-day at mobile user’s location • Cause Indicators • Cause Value (1-127) • Cause Location (1-10) • Coding Standard (ITU/ANSI) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  25. SS7 Protocols—IAM Parameters • IAM Initial Address Message Parameters • Nature of Connection Indicators (required) • Forward Call Indicators (required) • Calling Line Identification (required) • Called Party Number (required) • Redirecting Number (optional) • Redirection Information (optional) • Redirect Counter • Original Called Party Number (optional) • Transit Network (optional) • Charge Number (optional) • Information Integer (required if Charge Number present) • Hop Counter UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  26. SS7 Protocols—SAM Parameters • SAM Subsequent Address Message Parameters • Subsequent Number UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  27. SS7 Protocols—ACM Parameters • ACM Address Complete Message Parameters • Backward Call Indicators (required) • Charge Indicator (No Indication/Charge/No Charge) • Called Party’s Status Indicator (No Indication/Subscriber Free/Connect when Free) • Called Party’s Category (No Indication/Subscriber/Payphone) • Interworking Indicator (non-SS7 circuit somewhere in path) • ISDN All The Way (ISDN used end-to-end) • ISDN Access (terminating access is [not] ISDN) • Echo Control Device Indicator • Others UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  28. SS7 Protocols—ANM Parameters • ANM Answer Message • Backward Call Indicators (optional) • Connected Number (optional) • Redirection Information (optional) • Redirection Number (optional) • Redirection Number Restriction (optional) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  29. SS7 Protocols—REL Parameters • REL Release Message • Cause Indicators • Redirection Information (optional) • Redirection Number (optional) • Redirection Number Restriction (optional) • Redirection Counter (optional) UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  30. SS7 Protocols—RLC Parameters • RLC Release Complete Message • Cause Indicators UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

  31. Signaling System 7 (SS7) Next lecture on VoIP-related Issues UVSC CS 479R – Telecommunications and Voice Over IP Signaling System 7 Call Signaling

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