Private Branch Exchange PBX

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Private Branch Exchange (PBX)

• a single-line telephone set with a dial-tone line
  for each user will work but will not service all
  the needs and will be expensive
• many organizations now say that
  telecommunications is the number-two expense item
  in their corporate expense registers, second only
  to personnel costs

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Private Branch Exchange (PBX)

• larger organizations require the larger capacity
  and capability of a private branch exchange (PBX)
  
• Private Automated Branch Exchange (PABX)
• Computerized Branch Exchange (CBX)
• Digital Branch Exchange (DBX)
• Integrated Branch Exchange (IBX), and Nippon
  Electric Automated Exchange (NEAX).

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Private Branch Exchange (PBX)

• PBX is a private (customer owned and operated)
  branch exchange switches and routes calls
  internally or externally and provides a dial tone
  to the internal users
• These devices are computer systems that just
  happen to do voice the all-digital PBX will cost
  approximately 750 to 1000 per station (end-user
  device)

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Components of a PBX
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Analog Systems

• a signal is sent to the common control
• the system then returns a dial tone
• user then dials the digits for the party desired
• The digits, either rotary (pulse) or tone (DTMF),
  are sent down the wires to the telephone system.
• the telephone system kicks in and generates a
  request through the architecture to a trunk card
• The trunk card serves as the interface to the
  central office (CO) to request an outside dial
  tone
• The CO processes these digits

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Digital PBX

• All newer systems are basically digital
• A digital coder/decoder (codec) in the telephone
  set converts the analog voice conversation into a
  digital format
• If a call must go outside to the world, the PBX
  has to determine the best route to process the
  call onto telco. (Nortels Centrex service)

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Digital PBX
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Costs of a PBX

• Item Price Cost of hardware, software, training,
  all telephone sets, and interfaces with
  installation of the hardware 350,000
• Cost of wiring and installation for the building
  infrastructure 350,000
• Markup and profit 300,000
• Total 1,000,000

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Centrex Service

• Stands for central exchange, or PBX services
  provided from the central office (exchange)
• Centrex is usually rented on a line-by-line
  basis, month to month.
• Costs per line can range from 20 to 25 USD a
  month, depending on the company and the serving
  telco
• User must still buy the station equipment
  (telephone sets).

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Centrex Service
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Centrex Service Providers

• Bell Operating Companies
• Independent Operating Companies. These are such
  companies as Contel GTE, Centel, and
  Commonwealth.
• Resellers of Centrex service.Many arrangements
  have been made with resellers around the country
• Bell authorized agents. These are authorized
  agents of the LEC, but are not employees of the
  company.
• Consultants. These are special resellers who have
  a vested interest in their customers behalf, and
  a vested interest in the commissions they might
  receive from the LEC for the additions to the
  Centrex
• CATV companies
• Electric companies

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Peripheral Devices
The list of peripheral devices for the key
systems, PBX, and Centrex markets is virtually
unlimited. Automatic call distribution
Voice mail Automated attendant Call detail
recording Modem pools Multiplexers Head
sets Display sets (telephones) Paging
systems Least cost call routing Network
management systems Design tools Answering
machines
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Key Systems

• Key Systems
• Norstar System (Nortel Networks)
• Not centrally connected to a PBX
• Each telephone has access to outside lines by
  pressing the appropriate line number
• Central switch box controls this, located on site

• Digital signals, allows TDM
• Multiplexes multiple lines on 1 line
• Allows features such as music over intercom and
  paging etc

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Thin Client

• Bulk of the data processing occurs on the server
• Clients are usually comprised of screens and
  input devices only into a MAC
• Popular software Citrix Metaframe
• Useful for high demand applications only one
  expensive central server is required
• Windows XP Remote Administration