Principles of Voice & Data Lesson 1: Telephony Essentials Bellevue Community College Bob Young, Instructor

Terms & Explanations PSTN Public Switched Telephone Network

Terms & Explanations POTS "Plain Old Telephone Service" as in, "POTS line."

Terms & Explanations Phone Parts Transmitter - Mouthpiece Receiver - Earpiece

Terms & Explanations Full Duplex - voice can be sent in both directions at the same time. Half Duplex - voice can be sent in one direction at a time.

Terms & Explanations C.O. or CO Central Office

Terms & Explanations CPE Customer Premise Equipment CPE may be owned by the telco or by the customer

Terms & Explanations The "Last Mile" From the CO to the CPE

Terms & Explanations Outside Plant Telco equipment between the CO and the customer Poles, lines, vaults, etc.

Terms & Explanations On Hook The phone's handset is in the cradle. Open loop condition - no loop current.

Terms & Explanations Off Hook The phone's handset is out of the cradle. Closed loop condition - loop current is present.

Terms & Explanations RBOC Regional Bell Operating Company Divestiture of AT&T Formation of 7 RBOC's

The Seven RBOCS: 1)Ameritech 2)Bell Atlantic 3)BellSouth 4)NYNEX 5)Pacific Bell 6)Southwestern Bell 7)US WEST

RBOC Map, 1984

Terms & Explanations BOC Bell Operating Company Smaller, regional companies within the RBOC's – (22 BOC's)

Terms & Explanations IXC Interexchange Carrier After divestiture, IXC's handled long distance calls

Terms & Explanations LEC Local Exchange Carrier

Terms & Explanations LATA Local Access and Transport Area

Terms & Explanations ILEC Incumbent Local Exchange Carrier

Terms & Explanations CLEC Competing (or Competitive) Local Exchange Carrier

Terms & Explanations British Terms GPO - General Post Office BPO - British Post Office BT - British Telecom

Terms & Explanations ITU International Telecommunications Union

Terms & Explanations ITU-T International Telecommunications Union - Telecommunications Standardization Sector

Terms & Explanations Tandem Office A central office unit used primarily as an intermediate switching point for traffic between local central offices within the tandem area

Terms & Explanations Toll Tandem A central office unit used as the switching point between local CO traffic and toll (long distance) traffic

Terms & Explanations EO End Office A Central Office that connects directly to subscribers

Terms & Explanations Switches - Class 5 An End Office switch Provides local loop connections Call signaling and control - setup and knockdown

Terms & Explanations Switches - Class 4 A tandem switch Capable of connecting Class 5 switches

Terms & Explanations Switches - Class 3 A toll traffic switch Connects LEC's Capable of connecting Class 4 & 5 switches

Terms & Explanations PCM Pulse Code Modulation   -law (North America & Japan)  A-law (all other countries)  8 KHz sampling rate

Terms & Explanations PCM Issues Unrepresentative Sample Lack of Information Too Much Information

Terms & Explanations POP, PoP Point of Presence POI Point of Interconnection

Terms & Explanations FX Foreign Exchange FXO - Foreign Exchange Office FXS - Foreign Exchange Station

Terms & Explanations PBX Private Branch Exchange

Terms & Explanations KSU Key Service Unit or Key Switching Unit

Terms & Explanations DID Direct Inward Dialing as in, "DID Trunk"

Terms & Explanations DOD Direct Outward Dialing as in, "DOD Trunk"

Terms & Explanations Centrex Service A telco service in which the PBX hardware and functionality is provided and maintained by the telco

Terms & Explanations Analog Loop Start The call is originated by going off hook. Loop current initiates the call sequence.

Terms & Explanations E & M Trunks Voice and signaling are carried on separate wires E = "Ear" M = "Mouth"

Terms & Explanations Ground-Start Trunks The call sequence is initiated by grounding either the tip (from CO) or the ring wire (from PBX)

Terms & Explanations DSH Digital Signal Hierarchy DS0, DS1, DS3 T1, T3 T1 = Mbps

Terms & Explanations SF & ESF Super Frame (D4) Extended Super Frame

Terms & Explanations E-Carrier Europe uses E1's instead of T1's E1 = Mbps

Terms & Explanations SONET Synchronous Optical Network North American Standard Compare with SDH STS-1 = Mbps

Terms & Explanations STS & OC Synchronous Transport Signal Optical Carrier Exact same data rates Know both terms

Terms & Explanations STS-1 = OC-1 = Mbps STS-2 = OC-2 = Mbps STS-3 = OC-3 = Mbps etc.

SONET Physical Hierarchy

SONET Architecture

SONET Ring

Terms & Explanations SONET & OSI Model OSI Layer 1 Standard (Physical Layer)

Terms & Explanations More SONET Info SONET can be used for: ATM Gigabit Ethernet

Terms & Explanations SDH Synchronous Digital Hierarchy International Standard Don't confuse with DSH STM-1 = Mbps

Terms & Explanations Mbps STS-3 OC-3 STM-1

Terms & Explanations A & B Bit Signaling Digital equivalent of analog line signals Status of bits indicates idle or busy (on-hook, off-hook)

Stratum Clocks

Terms & Explanations Types of Timing Asynchronous Synchronous Plesiosynchronous

Terms & Explanations CSU/DSU Channel Service Unit Data Service Unit

Terms & Explanations SWC, WC Service Wire Center Wire Center

Terms & Explanations Distribution Frame Permanent wiring set up for easy cross connection

Terms & Explanations MDF Main Distribution Frame Typically at CO or large PBX

Terms & Explanations IDF Intermediate Distribution Frame Typically outside plant or customer premise

Terms & Explanations CDF Combined Distribution Frame Vertical blocks - CO lines Horizontal blocks - inside lines

Terms & Explanations MPOE Minimum Point of Entry Demarcation Point (Demarc)

Terms & Explanations NID Network Interface Device

Terms & Explanations Load Coils Reduces line loss Matches impedance Analog circuits only - Can't use in digital circuits

Terms & Explanations Bridge Tap Allows a cable to be run to more than one location Each circuit can only be used at one location

Terms & Explanations Call Processing Call setup Call maintenance Call completion (knockdown)

Call Signaling Dial tone Hz and 440 Hz at –12 dBm Pulse dialing - (10 pps standard) 40msec make, 60msec break, 600msec pause DTMF - (23 pps standard) Ring - (80-90 VAC at 20 Hz) Ringback Hz and 480 Hz at –20dBm, 0.2 sec on, 0.4 sec off Busy Hz and 620 Hz, 0.5 sec on, 0.5 sec off

Analog Problems Loss Echo Noise Crosstalk Delay

Terms & Explanations Echo Cancellation Acoustic Echo Control (wireless networks) Far End Echo Cancellation (long distance, satellite)