Powerpoints Telephone Flashcards
Define following:
Backplane
Main board where other circuits and power supplies are plugged into.
Bandwidth:
Difference in Hz between ↑ and ↓ frequency of a group or band of frequencies (300Hz and 3100Hz)
BPS:
Bits per second
Buffer:
Storage device in a computer system that compensates for a difference in the rate data flows during transmission.
Byte:
8 bits
Bit:
Unit of information in binary (1+0)
CO (Central Office):
Telecom facility where switching of the telephone calls is accomplished.
COS (Class of Service):
Features and outside line accessible to extensions within a PBX system based on the user’s privilege level.
CODEC:
Chip contained within the line unit, converts analog to digital and then uses Pulse Code Modulation (PCM).
Cross Connect:
Connections between two cables on IDF or MDF.
Flash (Hookflash):
Momentary depress and release a hookswitch (i.e. conference,transfer or another call)
Frequency:
Number of cycles completed per units of time measured in Hertz (Hz)
Ground Start:
Signaling that uses DC in a ground return path to request service.
Hertz:
Unit of measurement for frequency (1 Hz = one cycle per second)
Hookswitch:
Physical switch on the telephone base.
Inside Plant:
Within the company or inside customer’s facility.
ISDN (Integrated Services Digital Network)
Simultaneous Tx of voice and data over multiplexed communications circuits.
Interconnect:
Connection between CPE (customer’s primary equipment) and public switched network.
Intermediate Distribution Frame (IDF):
Extension of the MDF (main) and connected by multi-pair copper or fiber optics.
KSU (key service units):
Cabinet that contains the control modules associated with key telephone systems.
Local Exchange:
Switch office where outgoing/incoming calls are routed and directed to end user / end office.
Loop:
“Last mile” communication path between company and subscriber’s site, referring to the two halves of a communication circuit.
Loss:
Reduction of power in a circuit, measured in -dB.
Microwave:
RF between 1 and 20 GHz.
Modem: (modem/demodulator):
Changes digital signals into analog signals for Tx over the telephone lines.
Macmonic: ?
Memory aid that helps you remember something else or an abbreviation for an operation in a computer code.
MUX (multiplayer unit):
Device that contains two or more signals over the same link.
North American Dialing Plan:
Area code, central office code, subscriber number (651-555-1492 example).
Off Hook:
Hookswitch released, closing the tip/ring loop, signaling a request for service.
Outside Plant:
Poles, cables and wires outside the company and customer’s premises.
Packet:
Prat of a message that has some addressing information attached.
Packet Switching:
Form of multiplexing that allows decisions to be made on a packet-by-packet basis.
Port:
Point of access - physical part.
PBX (Private Branch Exchange):
Switching system on the customer’s property for internal calling and access to outside telephone network.
Protectors:
Mounted in MDF to guard outside damage to company (fuse, air gap, rare gas).
Pulse Dialing:
Quick on-hook/off-hook switches (rotary dialing).
Receiver:
Converts electrical energy to acoustic energy.
Redundant System:
Second complete system that activates upon failure of primary system.
RS-232:
Standard data input / output serial port.
Service Request:
Signaling to company that dial tone and a circuit are needed.
Signaling:
Exchange of control information.
Subscriber / Number:
Person/Company who has telephone number registered to them (subscriber number, last four digits of telephone number).
T1:
Circuit of 24 channels, channel called DSO with data rate of about 64 kbps, upload/download 1.544 Mbps.
Transmitter:
Converts sound waves into electrical energy.
Voice Frequency (Hum):
300-3400 Hz
Wire Gauge (AWG)
↑ gauge ↓ wire, 22 to 24 AWG
Ring Tone:
(+) 90-95 VAC (transmit -48VDC)
Tip/Ring;
Tip - Ground (service request)
Ring - (-48 Dial tone VDCm 90-95 Ring VAC)
Trunk:
Line between two switching stations (CO to CO, CO to PBX, PDX to PBX)
The three Trunk Types and define.
Loop start: On hook/off hook states presence of line circuit.
Ground start: Connection between PBX and CO (handshaking).
Direct inward dial: One-way incoming trunk from CO; allows outside caller to dial an extension (2-7 digit extensions).
Speech / Phone frequencies:
S) 100Hz - 6 kHz P) 300Hz - 3 kHz
Inband/Outband:
Analog (both) - In-band: range of human hearing Out-band: Outside of human hearing
Echo:
Noise that results from voice Tx, mismatches in Tx line impedance (fixed with echo canclls).
CODEC (code/decode):
Analog voice converted to digital, sound depends on CODEC and sampling rate.
Asynchronous/Synchronous Tx:
A) no time relation between ↑ send and receive Tx and ↓ loads faster than ↑ loads.
S) Time relationship between ↑ and ↓ loads; T1 and T3 use this model.
DSL:
Analog POTS circuit and data circuit on same pair; separated by frequency
ISDN:
International concept whose objective is a digital telephone network.
Digital Telephone Network
Not owned by anyone; end-to-end digital connection using twisted wires to connect subscriber to telco
DSO (digital signal zero):
Basic unit of measure for all ISDN based technologies.
Name ISDNs two types of channels and definition:
- Bearer channel (B channel) - carries the data.
2. Data channel (D channel) - the control channel - does not carry data.
ISDN BRI/PRI:
BRI - 2 B channels and 1 D channel
PRI - 23 B channels and 1 D channel. Caller ID is Tx on the D channel.
SS7 (signaling system 7)
Most widely used out-of-band signaling. Has entire OSI protocol suite attached to it.
SS7 (signaling system 7)
Most widely used out-of-band signaling. Has entire OSI protocol suite attached to it.
PBX (Private Branch of Exchange
Intermediate point between telephone sets and Co; Programming done remotely or locally; End user program changes in the system; Changes made via software or by moving cross connects.
Trunks vs. Lines (PBX)
Trunks feed switching equipment
Lines feed end devices
Apply to PBX based systems.
PBX System Capacity
Based on the number of trunk lines and station ports. The system is capable of:
First # - Max # of trunk ports
Second # - Max # of line ports.
24 x 48 = 24 trunks and 48 stations
Cross connects:
Makes moves, adds and changes easier
Hard key vs. soft key
Hard cannot be changed.
Soft can be changed or assigned by software.
QoS - Quality of Service:
Process of prioritizing
VoIP:
Sends voice over data network, converts voice signals to data. “Voice data” is prioritized over other traffic. Bypasses the Public Switched Network (PSN). Uses Session Initiation Protocol (SIP).
T1 Circuits:
24 voice/data circuits, 1.544Mbsp; Requires CSU/DSU (channel/data service unit); pulse Code Modulation or Frame Relay Tx used.
T3 Circuits:
672 multiplexed channels; equivalent to 28 T-1’s; rate 44.736Mbps
ISDN Circuit (BRI/PRI):
BRI (Basic Rate Interface) uncommon in US.
Two 64kbps B channels and one 64 kbps D channel.
PRI (Primary Rate Interface)
23 64kbps B channels and one 64 kbps D channel.
B = bearer carries the voice signals.
D = data controls info only.
Hotline:
Connects two telephones together.
Paging/Emergency Systems:
25 or 70v paging system.
Paging/Emergency Systems:
25 or 70v paging system.
