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Chapter Twelve Voice and Data Delivery Networks. 2 Introduction General, we used to go into either – data communications or voice communications Today,

Dec 20, 2015



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  • Chapter Twelve Voice and Data Delivery Networks
  • Slide 2
  • 2 Introduction General, we used to go into either data communications or voice communications Today, the two fields are merging Reasons: 1.Voice systems transfer computer data and networks support voice Thus, we need to the basic of voice telecommunications too! Basic conceptBasic concept (to p3)
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  • 3 Basic concept It has: The local loop is the telephone line that runs from the telephone companys central office to your home or business Central office building that houses the telephone companys switching equipment and provides a local dial tone on your telephoneCentral office For a local call, it has such a layouta layout If you place a long-distance call, the central office passes your telephone call off to a long-distance provider, a nation wide telephone systemnation wide telephone system Trunk special telephone line that runs between central offices and other telephone switching centersTrunk Usually digital, high-speed, and carries multiple telephone circuits Typically a 4-wire circuit, while a telephone line is a 2-wire circuit How to classify a call is a long distance or local call? LATA conceptLATA (to p4) (to p5) (to p7) (to p6) (to p8)
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  • 4 FIGURE 5-8 It is more efficient to connect telephones to a central office switch and then connect the central office switches together than to connect all telephones to each other.together than to connect all telephones A Local Environment building that houses the telephone companys switching Equipment and provides a local dial tone on your telephone (to p3)
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  • 5 FIGURE 5-11 Residential telephone cabling.telephone cabling (to p3)
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  • 6 FIGURE 5-10 The connection of the central offices in the nationwide telephone network.telephone network. A nation-wide environment Local Central Offices (to p3)
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  • 7 FIGURE 5-7 Diagram of a telephone call involving toll trunks and toll offices.trunks and toll offices Note: can be replaced by a switch office (to p3)
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  • 8 LATA concept The country is divided into a few hundred local access transport areas (LATAs) If your call goes from one LATA to another, it is a long-distance call and is handled by a long- distance telephone company If your call stays within a LATA, it is a local call and is handled by a local telephone company (note: This concept applied in USA only and not HK) Installing a telephone system/line (to p9)
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  • 9 Telephone System/Line When telephone company installs a line, it must not proceed any further than 12 inches into the building This point is the demarcation point, or demarc Modular connectors, such as the RJ-11, are commonly used to interconnect telephone lines and the telephone handset to the base When handset is lifted off base (off-hook), an off- hook signal is sent to the central office (to p10)
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  • 10 Telephone System/Line (continued) When off-hook signal arrives at central office, a dial tone is generated and returned to telephone When user hears the dial tone, they dial (or press) number The central office equipment collects dialed digits, and proceeds to place appropriate call Types of telephone systems (to p11)
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  • 11 Types of telephone systems Private Branch Exchange (PBX)Private Branch Exchange Automated Attendant Automatic Call Distributor Interactive Voice Response Key Telephone System Basic Telephone Systems ServicesSystems Services That offered by local operators Other Players in the MarketOther Players (to p20) (to p21) (to p24) (to p16) (to p15) (to p12) (to p18)
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  • 12 PBX Private Branch Exchange (PBX) common internal phone switching system for medium- to large-sized businesses Provides advanced intelligent features to users, such as: 4-digit internal dialing Special prefixes for WATS, FX, etc (private dialing plans) PBX intelligently decides how to route a call for lowest cost (to p13)
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  • 13 PBX (continued) More PBX features: Voice mail Routes incoming calls to the best station set (automatic call distribution) Provides recorded messages and responds to touch-tone requests (automated attendant) Access to database storage and retrieval (interactive voice response) VoIP (to p14)
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  • 14 PBX (continued) PBX components: CPU, memory, telephone lines, trunks Switching network Supporting logic cards Main distribution frame Console or switchboard Battery back-up system (to p11)
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  • 15 Automated Attendant Plays a recorded greeting and offers a set of options Lets the caller enter an extension directly (touch tone or voice) and bypass an operator Forwards the caller to a human operator if the caller does not have a touch tone phone Available as an option on a PBX (to p11)
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  • 16 Automatic Call Distributor When you call a business and are told all operators / technicians / support staff / etc. are busy and that your call will be answered in the order it was received Used in systems where incoming call volume is large, such as customer service, help desk, order entry, credit authorization, reservations, and catalog sales Early systems used hunt groups Original systems routed call to first operator in line (kept person very busy!) (to p17)
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  • 17 Automatic Call Distributor (continued) Modern systems perform more advanced functions, such as: Prioritize the calls Route calls to appropriate agent based on the skill set of the agent If all agents busy, deliver call to waiting queue and play appropriate message (like how long they may have to wait) Forward calls to another call center, or perform automatic return call (to p11)
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  • 18 Interactive Voice Response IVR is similar to automated attendant except: IVR incorporates a connection to a database (on a mainframe or server) IVR allows caller to access and/or modify database information IVR can also perform fax on demand (to p19)
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  • 19 Interactive Voice Response (continued) Common examples of IVR include: Call your bank to inquire about an account balance University online registration system Brokerage firm taking routine orders from investors Investment fund taking routine requests for new account applications A company providing employees with info about their benefit plans (to p11)
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  • 20 Key Telephone System Used within a small office or a branch office, a key telephone system (KTS) is an on-premise resource sharing device similar to a PBX Example key system might distribute 48 internal telephone sets over 16 external phone lines The business would pay for the 16 individual lines but have 48 telephone sets operating User selects outside line by pressing corresponding line button on key set (phone) (to p11)
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  • 21 Basic Telephone Systems Services Foreign exchange service (FX) - customer calls a local number which is then connected to a leased line to a remote site It can serve as discounted IDD for service agents Wide area telecommunications services (WATS) discount volume calling to local- and long- distance sitesWATS Off-premises extensions (OPX) dial tone at location B comes from the PBX at location A (to p11) (to p22)
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  • 22 Wide Area Telecomm Services Wide Area Telecomm Services (WATS) offers quantity discounts to high volumes of calls there are 3 basic categories: a) call direction (that is in-WATS or out-WATS) In-WATS (only allow users to call in to company) Out-WATS(only allows users to call out to company) (to p23)
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  • 23 b) Coverage The charges depends on band zone to which company has prescribed. In USA, it has 5 bands (1-5) c) Geographic regions three types 1) Intra-state (service provides on either in or out WATS, within subscribers home state) 2) Inter-state (applies to outside state boundary but within the country) 3) International (applies similar to IDD calls) (to p21)
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  • 24 Other Players in the Market Alternate operator services Pay phones, hotel phones Aggregator pulls a bunch of small companies together and goes after phone discounts Reseller rents or leases variety of lines from phone companies, then resells to customers Specialized mobile radio carriers mobile communication services to businesses and individuals, including dispatch, paging, and data services HK Telecomm Revolution ! (to p25)
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  • 25 Telecomm and Deregulation in HK Environment Prior 1995, all telecomm services in HK are franchised ( why need to cater for franchising?) HK Government opens up the telecomm markets of fixed network services in 1995. Franchised right to HK telecomm (now PCCW) expired on 1995. New operators fixed line tel line registered in 1995 HK telecom (PCCW) licensed on June 29, 1995 Hutchison Telecomm Ltd licensed on June 30, 1995 New World licensed on June 20, 1995 (to p26)
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  • 26 Telecomm and Deregulation in HK Environment (cont.) Deregulation of Mobile comm services In 23 Feb 1999, OFTA (Office for Telecomm Authority) announced the regulation of MNP (Mobile number portability) started on 1 March 1999, that a customer could retain of his/her mobile phone number as personal identity. Worldwide Regulatory agenciesRegulatory agencies Limitations of voice telecomm!Limita