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Lines and Trunks (Ch. 7) PBX (Ch. 9) Key Telephone Systems (Ch. 10)

Lines and Trunks (Ch. 7) PBX (Ch. 9) Key Telephone Systems (Ch. 10). ENGR 475 – Telecommunications Harding University Jonathan White. Lines. End Point End in terminals (telephones, modems, faxes) New term: FX0 – Foreign Exchange Office Connection to analog POTS 2 wire, typically analog

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Lines and Trunks (Ch. 7) PBX (Ch. 9) Key Telephone Systems (Ch. 10)

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  1. Lines and Trunks (Ch. 7)PBX (Ch. 9)Key Telephone Systems (Ch. 10) ENGR 475 – Telecommunications Harding University Jonathan White

  2. Lines • End Point • End in terminals (telephones, modems, faxes) • New term: FX0 – Foreign Exchange Office • Connection to analog POTS • 2 wire, typically analog • Called DS-0 • 64 Kbps • Nothing special

  3. Trunks • Connection between points • Carry many lines • Connects 2 intelligent switching systems • PBX/Centrex/CO • Digital • Multiplexed • Expensive

  4. DID • Direct Inward Dialing • Everyone has their own unique telephone number at a business • However, you don’t have enough incoming/outgoing lines to support all users at once. • Handled by the PBX (routing) • You don’t have to go through an operator.

  5. DOD • Direct Outward Dialing • Again, you don’t have to go through an operator. • Handled by the PBX

  6. WATS • Wide Area telephone service • Same thing as 800/888/877/866 service • A way to reduce long distance costs

  7. PBX - Review • Private Branch Exchange • Owned by an individual company • Performs call routing and switching • Allows the business to save money because not as many connections to the PSTN are provided. • Keeps calls between employees internal to the network. • How many lines would a call between employees normally use?

  8. PBX - Review • How does the individual telephone numbers within a PBX system work? • Takes the cooperation of the Telco and the organization. • Some trunks can be dedicated strictly to Direct Inward Dialing. • Page 179 graphic

  9. PBX Functions • DID / DOD • Auto Attendant • Call transfer • Speed Dialing • Voice mail • Follow-me • Call forwarding on absence • Call forwarding on busy • Music on hold • Automatic ring back

  10. PBX Functions • Night service • Automatic call distributor • Call waiting • Call pick-up • Call park • Conference call • Call accounting • Voice paging (PA system) • Custom greetings • Shared message boxes

  11. PBX Cost • http://cgi.ebay.com/NEW-SOHO-PBX-PABX-AUTOMATED-PHONE-EXCHANGE-4-x-16_W0QQitemZ230023614851QQihZ013QQcategoryZ11908QQrdZ1QQcmdZViewItem • Can be found cheaply • Others can be very expensive • Installation and maintenance can be expensive

  12. Asterisk • Open source implementation of a PBX • Runs on Windows/Linux/UNIX and performs all the features of a proprietary PBX: • DID/DOD, voice mail, conference calling, interactive voice response (phone menus), and automatic call distribution. • Runs on a standard desktop computer • Needs a special PCI card to attach to the PSTN or other analog phones (a modem will not work).

  13. Asterisk • Can also be used to run a VOIP network with connections to the PSTN • With VOIP, this can be incredibly cheap.

  14. Asterisk PCI card

  15. Asterisk PCI Cards • PCI cards exist in several flavors: • 1 inward/outward phone line ($20) • 2 inward/outward ($225) • 4 inward/outward ($380) • T1 connection (24 inward/outward) ($890) • Very comparable in price to the cheapest of proprietary PBX’s

  16. Asterisk Analog PCI Hubs • Act as the Main Distribution Frames • Kind of like a router or hub • Allow the users of analog telephones to connect to the PBX server • Necessary if you want to run a non VOIP network • Cost: 12 port ($1400) • Not many people actually run analog Asterisk • http://www.voicetronix.com/hda.htm#features

  17. Non PCI Switches • Called Channel Banks • Connects many phone lines to 1 main trunk • Not incredibly expensive. • Provide the multiplexing/demultiplexing

  18. Channel Banks

  19. VOIP Asterisk • If the PBX is already running digitally, why not run digital phones using VOIP? • Phones can be computers • Or special VOIP phones • Instead of buying a $1400 switch, you can buy an Ethernet switch for incredibly cheap.

  20. Skype • Allows computer to computer conversations that only cross the Internet. • There’s one main difference between Skype and Asterisk. • Skype is free or almost free. • Skype has very good security.

  21. Centrex • Owned by the Telco • Same features as a PBX • Features are leased by businesses • Each user has their own external phone line.

  22. PBX/Centrex Boxes

  23. Key Telephone Systems • Multi-line telephone system used in SMALL office environments • Very old technology • Similar to a PBX. • Many telephone lines come into certain phones. A light comes on if the line is busy. A user takes control of a line by pressing a button.

  24. Key Telephone Systems • Provided intercom capabilities. • Often 6, 12, or 25 lines would come into a phone. • In North America, these type of phones were known as 1A2. • They are still manufactured and supported today, though they are rapidly becoming outdated.

  25. Key Telephone Systems

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