Subscriber NumberNational ISDN Number International ISDN Number max 15 dig... E.164 numberingCountry Code National Destination Number Subscriber Number National ISDN Number International
Trang 1Digital Telephony
Chapter 7
Signaling
Trang 2Subscriber Number
National ISDN Number International ISDN Number (max 15 dig.)
32 32 32 33 1 1
61 2 47 4 403 905
61 36 24 6736476 5819327 68243456
363 XXXX
890 XXXX
Trang 3E.164 numbering
Country
Code
National Destination Number
Subscriber Number
National ISDN Number International ISDN Number (max 15 dig.)
32 32 32 33 1 1
61 2 47 4 403 905
61 36 24 6736476 5819327 68243456
363 XXXX
890 XXXX
Trang 44 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: 8 digits = 10 000 000 numbers
» Mobile : 9 digits embedded in fixed ranges
• 42 XXXXXX : Liège
• 47 XXXXXXX : Proximus – France : CC = 33, Length = 9 digits – UK : CC = 44, Length = 10 digits – North America : CC = 1, Length = 10 digits
Trang 5Numbering vs Dialing
• Numbering plan : specifies structure and capacity
in addresses for PSTN/ISDN/GSM
• Dialing plan : specifies the way numbers are
» 03346824058 : access point in Antwerp
» 0033468240587 : access point in France
» 080234567 : access point in Stavelot
» 080023456 : freephone number
Trang 6» 19XX : Network specific applications
• 3-digit Access Codes : Common to all operators
– 100, 101, 105, 112, …
Trang 7Full dialing
Belgium 2001
• Keep original 8 digit numbering plan
• Abandon local dialing with 6 or 7 digits within zone
• Dial full national number with 0 prefix
• Benefits : enables new ranges of numbers
– PQ 0 XX XXX or P 0 XXX XXX
– PQ 1 XX XXX or P 1 XXX XXX
– PQ 9 XX XXX or P 9 XXX XXX
Trang 8• Cost :
– Operators : 1 to 10 € per customer
– Customers : 5 to 10 times more…
• Status : frozen…
Trang 9Telephone Exchange
Switching Matrix
Register Register Register Register
Trang 11Signaling 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
Trang 13The Telephone Network
673
Non-geographic Numbering 6234567
4776970
6736476
database
0800
Trang 1414 J.Tiberghien - VUB
The Telephone Network
Number portability
Ported numbers
Trang 15The Telephone Network
Number portability
Ported numbers
Trang 1616 J.Tiberghien - VUB
The Telephone Network
Number portability
Ported numbers
Trang 17The Telephone Network
Number portability
Ported numbers
Trang 1818 J.Tiberghien - VUB
The Telephone Network
Number portability
Ported numbers
Trang 19The Telephone Network
Carrier selection
• through prefix
• through preselection
Trang 2020 J.Tiberghien - VUB
SS7 Layered Model
Message Transfer Part level 1 Message Transfer Part level 2 Message Transfer Part level 3 Signaling Connection Control Part
ISDN - UPTransactions
MTP : Connectionless service for short response times
SCCP : Connection oriented service for applications requiring
reliable network service
Trang 21Message Transfer Part
• Layer 1 : over redundant channels
– any physical channel, digital or analog (with modem)
• Layer 2 : 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 3 : Connectionless
– Signaling Link Selection for load balancing and
route consistency
Trang 2222 J.Tiberghien - VUB
ISDN-UP Call signalling
Alerting Connect Set-up
Disconnect
Release Release confirmed
Exchanges
End to end B channel usage