Điện tử viễn thông c3 3 báo hiệu (signaling) mangcmkenh khotailieu

Digital Telephony Chapter Signaling J.Tiberghien - VUB E.164 numbering Country National Code Destination Number Subscriber Number National ISDN Number International ISDN Number (max 15 dig.) 32 32 32 33 1 61 47 403 905 61 36 24 6736476 5819327 68243456 363 XXXX 890 XXXX J.Tiberghien - VUB E.164 numbering Country National Code Destination Number Subscriber Number National ISDN Number International ISDN Number (max 15 dig.) 32 32 32 33 1 61 47 403 905 61 36 24 6736476 5819327 68243456 363 XXXX 890 XXXX J.Tiberghien - VUB E.164 numbering • National numbering plan – Open : variable length – mostly abandoned – Closed : length determined by first digits • Length indicates potential capacity in numbers – Belgium » PSTN/ISDN: digits = 10 000 000 numbers » Mobile : digits embedded in fixed ranges • 42 XXXXXX : Liège • 47 XXXXXXX : Proximus – France : CC = 33, Length = digits – UK : CC = 44, Length = 10 digits – North America : CC = 1, Length = 10 digits J.Tiberghien - VUB Numbering vs Dialing • Numbering plan : specifies structure and capacity in addresses for PSTN/ISDN/GSM • Dialing plan : specifies the way numbers are dialed by users – Prefixes : » 0, 00, » + = symbolic code for international prefix – Examples : dialing in Belgium » 03346824058 : access point in Antwerp » 0033468240587 : access point in France » 080234567 : access point in Stavelot » 080023456 : freephone number J.Tiberghien - VUB Special Codes • Carrier Selection Codes – 15XX or 16XX • 4-digit Access Codes : usage specific to operator – Belgacom : » 12XX, 13XX, 14XX : Historical services » 17XX : access to data networks » 18XX : Access to VPN » 19XX : Network specific applications • 3-digit Access Codes : Common to all operators – 100, 101, 105, 112, … J.Tiberghien - VUB Full dialing Belgium 2001 • • • • Keep original digit numbering plan Abandon local dialing with or digits within zone Dial full national number with prefix Benefits : enables new ranges of numbers – PQ XX XXX or P XXX XXX – PQ XX XXX or P XXX XXX – PQ XX XXX or P XXX XXX J.Tiberghien - VUB One digit extension Belgium : to digits • Goals : – more structured and comprehensive numbering » : mobile (done) » : personal number (future) » : freephone » : premium services – More available numbers (?) • Cost : – Operators : to 10 € per customer – Customers : to 10 times more… • Status : frozen… J.Tiberghien - VUB Telephone Exchange trunk lines + Inter-office signaling Line Circuit Register Line Circuit Line Circuit Switching Matrix Register Register Line Circuit Line Circuit Register Control Computer J.Tiberghien - VUB The Telephone Network Geographic Numbering 4776970 477 6234567 62X 538 673 6736476 643 629 64X 10 6292905 6433180 J.Tiberghien - VUB Signaling system generations • SS1 - SS5 : Analog call forwarding between exchanges • SS6 : First digital signaling system – monolithic communications system (no layers) – Full mesh of virtual circuits, based on 2400 b/s links • SS7 : Signaling system for the intelligent network – uses any digital links, satellites included – layered, OSI inspired, network architecture – supports "intelligent network" applications » Non-geographic numbers (800) » CLIP, Call forwarding, Conference calls, etc » Number portability » Carrier selection » Mobility & roaming • IP ??? 11 J.Tiberghien - VUB The Telephone Network Geographic Numbering 4776970 477 6234567 62X 538 673 6736476 643 629 64X 12 6292905 6433180 J.Tiberghien - VUB The Telephone Network Non-geographic Numbering 6234567 4776970 477 database 0800 62X 538 673 6736476 643 629 64X 13 6292905 6433180 0800 12345 J.Tiberghien - VUB The Telephone Network Number portability Ported numbers 14 J.Tiberghien - VUB The Telephone Network Number portability Ported numbers 15 J.Tiberghien - VUB The Telephone Network Number portability Ported numbers 16 J.Tiberghien - VUB The Telephone Network Number portability Ported numbers 17 J.Tiberghien - VUB The Telephone Network Number portability Ported numbers 18 J.Tiberghien - VUB The Telephone Network Carrier selection • through prefix • through preselection 19 J.Tiberghien - VUB SS7 Layered Model OMAP ASEs Transactions ISDN - UP 4-5-6 Signaling Connection Control Part Message Transfer Part level Message Transfer Part level Message Transfer Part level MTP : Connectionless service for short response times SCCP : Connection oriented service for applications requiring reliable network service 20 J.Tiberghien - VUB Message Transfer Part • Layer : over redundant channels – any physical channel, digital or analog (with modem) • Layer : HDLC like data link protocol – Error correction » Sliding window (127) with “go back n” » Preventive cyclic retransmission – Link failure detection » Leaky bucket error counter » Fill-in signaling frames • Layer : Connectionless – Signaling Link Selection for load balancing and route consistency 21 J.Tiberghien - VUB ISDN-UP Call signalling Exchanges Set-up Alerting Connect End to end B channel usage Disconnect Release Release confirmed 22 J.Tiberghien - VUB