ECElec4 Midterms
SUPERVISION
the CO must provide functions that monitor local loop conditions and other services.
Outlets
the set of output circuits are called the _____________
Equated Busy-Hour Call
(EBHC)
crossbar switch
A ___________ connects n inputs to m outputs in a grid, using electronic microswitches (transistors) at each crosspoint
Telecommunication network
A _________________ is a group of systems that establishes a distant call.
Holding Time
Also, the average duration occupancy of one or more paths by calls
1960s
Businesses adapt PBX Systems
physical layer
Circuit switching takes place at he ____________
dual-tone multifrequency
DTMF
1989
First flip-phone released-targeted at wealthy consumers and priced at 3000 $
multiple crosspoints
Each crosspoint in the middle stage can be accessed by ____________ in the first or third stage
2002
First Blackberry with cellphone service released
space-division switching
In ________________, the paths in the circuit are separated from one another spatially.
space division switching
In __________________, a dedicated path is established between the calling and the called subscribers for the entire duration of the call.
reserved
In circuit switching, the resources need to be __________ during the setup phase; the resources remain dedicated for the entire duration of data transfer until the teardown phase.
Local Access Transport Area
LATA
Holding Time
Length of time during which a call engages a traffic path or channel
black and yellow
Many telephone cables into a home or an ofi ce also contain a second twisted pair if a separate telephone line is to be installed. These wires are usually color-coded _____________.
wireless cell phone
Most homes now have a least one ______________ that is the sole telephone connection.
calling rate
Number of calls per unit time
Open Shortest Path First
OSPF
Stored Program Control
SPC
Circuit switching
Switching method used by the physical layer
Traffic Unit
TU
ringer
The ________in most older telephones is an electromechanical bell. A pair of electromagnetic coils is used to operate a small hammer that alternately strikes two small metallic bells.
calling rate
The average number of calls placed during the busy hour
voice communication
The primary purpose of the telephone system is to provide ________________
central switch
When N gets larger, it is economical to use a ____________
hierarchical switching network
When N is very large and the stations are spread over wide geographical area, one or more levels of intermediate switching is more economical. This leads to a ______________, consisting of a network of switches.
tone
When an incoming call is received, a signal from the central office causes the bell or ringer to produce a ___________.
Space switching arrays
___________ are used in older analog as well as modern digital switching exchanges.
Packet switching
_____________ is popular in computer communication networks.
Bus and Ring topology
alternative methods that connect devices in a network but is not enough especially in long distance communication
Public
anyone can connect to the network
trunk lines
connection between COs
central office
connects any two individual telephones.
access system
consists of the access line to the customer and termination equipment at the end office
network
is a set of connected devices
rectangular array of crosspoints
A single-stage space switch consists of a ______________.
Customer Premises Equipment
CPE
space-division switch, time-division switch
Circuit switching today can use either of two technologies:
Agner Krarup Erlang
Erlang is named after _________
Hundred Call-Second per Hour
HCS
Internet Engineering Task Force
IETF
time division switching
In _____________, sampled values of speech signals are transferred at fixed intervals.
setup phase
In circuit switching, the resources need to be reserved during the ___________; the resources remain dedicated for the entire duration of data transfer until the teardown phase.
IGP
Interior Gateway Protocols
Erlang
One ________ is equal to the number of call-seconds divided by 3600, which is equal to a fully loaded (voice) circuit over a one-hour period.
late 1990s
PBX systems begin integrating VoIP
Message Switching
Switching method used by the application layer
Electronic Switching systems
The _____________ are operated with the help of a processor or a computer which control the switching timings.
Step-by-step switching system
The _____________ is also called the Strowger switching system after its inventor A B Strowger.
wired telephone
The _____________ is gradually becoming history.
switching stations
The ______________ provide connection between different subscribers. Such switching systems can be grouped to form a telecommunication network.
Subscriber Lines
The lines that run to the Subscriber premises are called the _______________
earpiece
The receiver, or ___________, is basically a small permanent-magnet speaker.
100 ohms
The resistance of the telephone itself also varies over a relatively wide range. It can be as low as_________________ and as high as 400 ohms, depending upon the circuitry.
Connection setup, Data TrAnsFer, and connection tear down
Three phases of circuit-switched network
circuit switching, packet switching.
Two distinct switching techniques are employed in communication networks:
Broadcast System
___________ is a one-way communication system
Optimal Routing
_____________ is routing calls from their originating point directly to the terminating mobile without passing (through) Home.
circuit-switched network
A _____________ is made of a set of switches connected by physical links, in which each link is divided into n channels.
single-stage space switch
A ______________ consists of a rectangular array of crosspoints.
call-minute
A ______________ is equivalent to 1 call with a duration of 1 minute
calling subscriber
All the subscribers need to have a connection with the switching system, which makes or breaks any connection, requested by the ______________
transmitter and receiver
A telephone set has a handset that contains a microphone and a speaker, better known as a transmitter and a receiver.
dialing and signaling
All____________ operations are also carried on this single twisted-pair cable.
1871
Antonio Meucci's invention of the telephone in ___________ began the era of telecommunication and marked the start of the telephone timeline that continues to grow to this day.
10000
As many as ___________ telephone lines can be connected to a single central office
4000 Hz
An unloaded twisted pair has an upper cutoff frequency of about ________. But this cutoff varies considerably depending upon the overall length of the cable.
1877
Bell Telephone Company founded. 3000 private
DynaTAC
In 1973, first non-car mobile phone (_________) appears
packet switching
In ____________, messages to be passed are packetized and the connection is used by a call as and when packets are ready
dedicated
In circuit switching, the resources need to be reserved during the setup phase; the resources remain ________ for the entire duration of data transfer until the teardown phase.
teardown phase.
In circuit switching, the resources need to be reserved during the setup phase; the resources remain dedicated for the entire duration of data transfer until the ____________
Traffic engineering
It provides the basis for estimating immediate requirements
Multiprotocol Label Switching
MPLS
Fully Connected Networks
Networks with point-to-point links among all the entities are known as _____________________
Private Branch Exchange
PBX
Subscriber Line Interface Circuit
SLIC
Switching Matrix
The hardware used to establish connection between inlets and outlets is called the____________ or the Switching Network.
microphone
The transmitter is the ____________ into which you speak during a telephone call.
HANDSET
This unit contains a microphone for the transmitter and a speaker or receiver.
Voice over Internet Protocol
VoIP
Centum Call Seconds/Century Call Seconds
CCS
Hundred Call-Second per Hour
CCS is also called __________
Central Office
CO
off the hook
When a call is to be made or to be received, the handset is taken ____________. This closes the switch and connects the telephone circuitry to the local loop. The direct current from the central office is then connected to the telephone, closing its circuits to operate.
connection set-up
creating dedicated channels between the switches
central office
it is where switching circuit is done
AUTOMATIC VOICE LEVEL ADJUSTMENT
. Because of the wide variation in the different loop lengths of the two telephones connected to each other, the circuit resistances will vary considerably, thereby causing a wide variation in the transmitted and received voice signal levels.
EBHC
1 ________ is the average intensity in one or more traffic paths occupied in the busy-hour by one 2-min call or an aggregate duration of 2 min
TU
1 __________ is the average intensity in one or more traffic paths carrying an aggregate traffic of 1 call-hour in 1 hour (the busy hour unless otherwise specified.
1946
250000 women employed as switch board operators for public services and businesses
2011
31% of installed business lines in North America are VoIP based
2015
66.5%of North American businesses lines predicted to be VoIP based
2008
80% of all new PBX Lines are VoIP based
varistor
A )___________ is a nonlinear resistance element whose resistance changes depending upon the amount of current passing through it.
Smart Link
A __________ is a predefined destination path used on a campaign. They are useful for creating default redirects defined by paths set up by the user.
call-second
A __________ is equivalent to 1 call with a duration of 1 second.
switch hook
A _____________ is a double-pole mechanical switch that is usually controlled by a mechanism actuated by the telephone handset.
routing protocol
A _______________ specifies how routers communicate with each other, distributing information that enables them to select routes between any two nodes on a computer network.
analog baseband transceiver
A basic telephone or telephone set is an _____________.
microphone and speaker
A telephone set has a handset that contains a ________________, better known as a transmitter and a receiver.
Switching
Alexander Graham Bell recommended the ___________________ between the subscribers using a switching office that maintains the telephone connections.
switching system
All the subscribers need to have a connection with the ______________, which makes or breaks any connection, requested by the calling subscriber.
unloaded twisted pair
An ___________ has an upper cutoff frequency of about 4000 Hz. But this cutoff varies considerably depending upon the overall length of the cable.
Arrival Rate
Average number of calls initiated per unit time (e.g. attempts per hour) also known as ________
Battery Over-voltage protection Ringing Supervision Coding Hybrid Test signals
BORSCHT
dedicated path
Circuit switching provides a _______________ between the two end points.
Customer Premises Equipment Access Line (Local Loop) Transport Core Central Office/Switch Points of Presence
Elements of the Public Switched Telephone Network (PSTN)
1996
First Voice Over Internet Protocol (VoIP) system introduced - Volitech.
1997
First hosted PBX launched, Virtual PBX, Inc.
1881
First long-distance phone service
1878
First manual switchboard debuts in Boston.
1946
First mobile car-based telephone system introduced
1973
First non-car mobile phone (DynaTAC) appears
Late 2000s
Full integration of landlines, cellular, softphones, and VoIP into hosted PBX business phone systems
Electromechanical Switching Systems
Here, mechanical switches are electrically operated.
Electronic Switching Systems
Here, the usage of electronic components such as diodes, transistors and ICs are used for the switching purposes.
low in number
If the number of telephone sets or the subscribers present is _____________, the type of connection will be a little complex.
multiple paths
If we can allow _____________ inside the switch, we can decrease the number of crosspoints.
Volitech
In 1996, First Voice Over Internet Protocol (VoIP) system introduced - ________
operators
In manual switching, the connections were made by the _____________ at the telephone exchanges in order to establish a connection.
tone dialing system
In most modern telephones, a _________ is used. Known as the dual-tone multifrequency (DTMF) system, this dialing method uses a number of pushbuttons that generate pairs of audio tones that indicate the digits called.
dual-tone multifrequency
In most modern telephones, a tone dialing system is used. Known as the _____________ system, this dialing method uses a number of pushbuttons that generate pairs of audio tones that indicate the digits called.
pulse dialing system
In older telephones, a ___________ was used. A rotary dial connected to a switch produced a number of on/off pulses corresponding to the digit dialed. These on/off pulses formed a simple binary code for signaling the central office.
packetized
In packet switching, messages to be passed are ______________ and the connection is used by a call as and when packets are ready
sidetone
In practice, the hybrid windings are set up so that a small amount of the voice signal produced by the transmitter does occur in the receiver.
call-minute
In telecommunication, a __________ is a unit used to measure communications traffic density.
call-second
In telecommunication, a ____________ is a unit used to measure communications traffic density.
A. B. Strowger
Inventor of the Strowger switching system
Circuit switching
It can also be used for data communications by employing modems which convert data to voice band signals.
Traffic Intensity
It can be measured by averaging periodic counts of the number of calls present during the period, or by summing the duration of calls within the period and dividing by the period length.
single-stage space switch
It can connect an arbitrary idle inlet to an arbitrary idle outlet.
Subscriber Line Interface Circuit
It consists of basic circuits that power the telephones and provides all the basic functions such as ringing, dial tone and dialing supervision
Telephone Traffic
It is also a probability that someone needs to make a call
Traffic Intensity
It is also called TRAFFIC LOAD.
Traffic engineering
It is an analysis of the amount and type of use the proposed system will receive in.
Circuit switching
It is ideal for providing normal voice communications.
Traffic Quantity
It is of particular use for billing or other volume calculations but is not useful by itself.
Traffic Intensity
It is the average number of calls present during a period of time.
Call Intensity
It is used in estimating traffic loads on control equipment where the duration of calls on the traffic-carrying paths is irrelevant.
Traffic Quantity
It represents the total number of channel uses in units of time.
Telephone Handsets SLICs Switching Systems Trunk lines and other media
Major Elements of the Telephone System
teletrofono
Meucci, a brilliant Italian inventor, filed the first one-year renewable notice of an impending patent of the "___________" on December 28, 1871.
December 28, 1871
Meucci, a brilliant Italian inventor, filed the first one-year renewable notice of an impending patent of the "teletrofono" on __________________.
October 1889
Meucci, the true inventor of the telephone, passed away in ___________, before Bell's patent could be dispelled on grounds of fraud.
Erlang
One __________ is the traffic intensity represented by an average of one circuit busy out of a group of circuits over some period of time
Point of Presence
POP
Plain Old Telephone System
POTS
router protocol
Routers connect networks using the Internet Protocol (IP), and OSPF (Open Shortest Path First) is a ____________ used to find the best path for packets as they pass through a set of connected networks.
traffic directing
Routers perform the "____________" functions on the Internet; data packets are forwarded through the networks of the internet from router to router until they reach their destination computer.
data packets
Routers perform the "traffic directing" functions on the Internet; ___________ are forwarded through the networks of the internet from router to router until they reach their destination computer.
two-wire, twisted-pair cable
Standard telephones (Subscribers) are connected to the telephone system by way of a ____________ that terminates at the local exchange or central office (CO)
LINE SIDE INTERFACE
Subscriber Line Interface Circuit is also known as the ____________
March 1876
Subsequently, Alexander Graham Bell, who ran experiments at the same laboratory as Meucci, was granted a patent in ___________.
Alexander Graham Bell
Subsequently, ___________, who ran experiments at the same laboratory as Meucci, was granted a patent in March 1876.
on-demand connection
Switching is the provision of an _______________ between two end points.
Packet Switching
Switching method used by the data-link layer
Packet Switching
Switching method used by the network layer
Strowger switching system
The Step-by-step switching system is also called the ______________
receiver
The ________ or earpiece, is basically a small permanent-magnet speaker.
dc power
The _________ for operating the telephone is generated at the central office and supplied to each telephone over the local loop.
hybrid
The _________ is a transformer-like device that is used to simultaneously transmit and receive on a single pair of wires.
transmitter
The _________ is the microphone into which you speak during a telephone call.
frequency response
The _________ of the local loop is approximately 300 to 3400 Hz.
local loop length
The __________ can vary from a few thousand feet up to about 18,000 ft.
dialing circuits
The ___________ provide a way for entering the telephone number to be called.
local loop resistance
The ____________ depends considerably on the length of the twisted pair between the telephone and the central office
Erlang
The _____________ is a dimensionless unit that is used in telephony as a measure of offered load or carried load on service-providing elements such as telephone circuits or telephone switching equipment.
ringer
The _____________ is either a bell or an electronic oscillator connected to a speaker. It is continuously connected to the twisted pair of the local loop back to the central office.
telephone system
The ______________ is also widely used for many other purposes, including facsimile transmission, TV transmission, and computer data transmission.
telephone system
The ______________ is the largest and most complex electronic communication system in the world.
telephone system
The ______________ uses just about every type of electronic communication technique available
Crossbar switching systems
The _______________ have hard-wired control subsystems which use relays and latches.
complete electric circuit
The circuits in the telephone and at the central office form a __________, or loop.
loop
The circuits in the telephone and at the central office form a complete electric circuit, or _________.
analog
The circuits in the telephone and at the central office form a complete electric circuit, or loop.
dc and ac signals
The circuits in the telephone and at the central office form a complete electric circuit, or loop.
telephone system
The connections from the central office go to the "____________" represented by the large "cloud."
cloud
The connections from the central office go to the "telephone system" represented by the large "___________."
Strowger system
The control functions in a ____________ are performed by circuits associated with the switching elements in the system.
local loop
The dc power for operating the telephone is generated at the central office and supplied to each telephone over the ___________.
Holding Time
The duration of occupancy of a traffic path by a call.
300 to 3400 Hz
The frequency response of the local loop is approximately _________.
Switching Network
The hardware used to establish connection between inlets and outlets is called the Switching Matrix or the ______________.
side tone
The hybrid also provides a __________ from the transmitter to the receiver so that the speaker can hear her or his voice in the receiver. This feedback permits automatic voice-level adjustment.
full duplex
The hybrid permits _________, i.e., simultaneous send and receive, analog communication on the two-wire line.
induction coil
The hybrid, which is also sometimes referred to as an __________, is really several transformers combined into a single unit.
switching systems
The introduction of ________________ reduced the complexity of wiring and made the telephony hassle-free.
18000 ft
The local loop length can vary from a few thousand feet up to about _______________.
crosspoints
The major limitation of crossbar switch is the number of ___________ required.
good system
The network connection cannot be simply made with telephone sets and bunch of wires, but a _________________ is required to make or break a connection. This system is known as the Switching System or the Switching Office or the Exchange.
Switching System
The network connection cannot be simply made with telephone sets and bunch of wires, but a good system is required to make or break a connection. This system is known as the Switching System
call rate
The number of times a route or traffic path is used per unit period, or, more properly defined, "the call intensity per traffic path during the busy hour"
full duplex analog communication
The original telephone system was designed for ________________ of voice signals.
electrical path
The primary function of a switching system is to establish an __________ between a given inlet-outlet pair.
two-wire transmission
The regular telephone instrument uses the same pair of wires for both transmitting (talking) and receiving (listening). This is known as ___________
400 ohms
The resistance of the telephone itself also varies over a relatively wide range. It can be as low as 100 ohms and as high as __________, depending upon the circuitry.
electromechanical bell
The ringer in most older telephones is an ___________. A pair of electromagnetic coils is used to operate a small hammer that alternately strikes two small metallic bells.
Inlets
The set of input circuits of an exchange are called _________
telecommunication network
The switching stations provide connection between different subscribers. Such switching systems can be grouped to form a _________________
Telephone Exchange
The switching system, which is also called the ______________, takes care of establishing the calls.
Trunks
The switching systems are connected using lines called the ____________
telecommunication network.
The switching systems are part of a ________________
green
The tip wire is _________ and is usually connected to ground; the ring wire is red.
red
The tip wire is green and is usually connected to ground; the ring wire is _____
hybrid
The transmitter and receiver are independent units, and each has two wires connecting to the telephone circuit. Both connect to a special device known as the _________
tip and ring
The two wires used to connect telephones are labeled _____________.
local loop
The two-wire, twisted-pair connection between the telephone and the central office is referred to as the _________ or subscriber loop. Also referred to as the last mile or the first mile.
subscriber loop
The two-wire, twisted-pair connection between the telephone and the central office is referred to as the local loop or _______________. Also referred to as the last mile or the first mile.
last mile
The two-wire, twisted-pair connection between the telephone and the central office is referred to as the local loop or subscriber loop. Also referred to as the ___________ or the first mile.
first mile
The two-wire, twisted-pair connection between the telephone and the central office is referred to as the local loop or subscriber loop. Also referred to as the last mile or the ___________.
ac voice signals
The_________ are transmitted along with the dc power.
Crossbar switching systems
These subsystems have limited capability and it is virtually impossible to modify them to provide additional functionalities.
Preset Smart Links
This feature eliminates the need to manually setup the Redirect tab where preset Smart Links can be used instead to redirect traffic across multiple campaigns.
telephone number
This means that each telephone must have a unique identification code—the 10-digit _________________ assigned to each telephone.
MPLS
This process consumes time and hardware resources, potentially resulting in degraded performance for real-time applications such as voice and video.
sidetone
This provides feedback to the speaker so that she or he may speak with normal loudness.
space-division switching
This technology was originally designed for use in analog networks but is used currently in both analog and digital networks.
four-wire system
This two-wire system, however, is converted to a ____________, which employs separate paths for each of the directions, to facilitate long distance transmission and switching.
digital techniques
Today, the telephone system is still primarily used for voice, but it employs mostly _____________, not only in signal transmission but also in control operations.
teletraffic engineering and traffic management
Traffic engineering is also known as ______________.
Western Union Affiliate Laboratory
Unfortunately, Meucci's financial troubles combined with misfortune led to the disappearance of his working telephone models from _____________
Erlang
Unit of: Offered load, carried load
Erlang
Voice traffic is measured by the ________, which is the unit of (telephone) traffic intensity.
on the hook
When the handset is "___________," the hook switch is open, thereby isolating all the telephone circuitry from the central office local loop.
open
When the handset is "on the hook," the hook switch is __________, thereby isolating all the telephone circuitry from the central office local loop.
mesh network
When the number of stations N is small, we can simply interconnect the stations with a ____________
switching systems
With the introduction of ______________, the need for traditional connections between the subscribers reduced.
CCS
_________ is a unit of traffic intensity equal to 1/36 of an Erlang
Erlang
_________ is defined as the number of (telephone) call arrivals per mean service time.
Routers
_________ perform the "traffic directing" functions on the Internet; data packets are forwarded through the networks of the internet from router to router until they reach their destination computer.
General routing
__________ :traffic flow between nodes s and d can be split arbitrarily over the paths between s and d
IGP
__________ are protocols aimed at traffic moving around within a larger autonomous system network like a single enterprise's network, which may in turn be made up of many separate local area networks linked through routers.
Telephone trunk lines
__________ are the ones that enable users to make outgoing calls / receive incoming calls in an organization.
Blocking
__________ refers to times when one input cannot be connected to an output because there is no path available between them— all the possible intermediate switches are occupied
Multiprotocol Label Switching
___________ is a protocol-agnostic routing technique designed to speed up and shape traffic flows across enterprise wide area and service provider networks.
OSPF
___________ is designated by the Internet Engineering Task Force (IETF) as one of several Interior Gateway Protocols (IGPs)
Telephone Traffic
___________ is determined by the number of subscribers trying to contact another subscriber
TELEPHONY
___________ is the art of projecting a sound wave thru a given apparatus, transforming the sound wave into an electrical wave, passing the electrical wave over a wire or circuit, and then transforming the electrical wave back into sound wave.
MPLS
___________ was created in the late 1990s as a more efficient alternative to traditional IP routing, which requires each router to independently determine a packet's next hop by inspecting the packet's destination IP address before consulting its own routing table.
Antonio Meucci
___________'s invention of the telephone in 1871 began the era of telecommunication and marked the start of the telephone timeline that continues to grow to this day.
Preset Smart Links
____________ can be used across multiple campaigns once they are configured to simplify campaign setup.
Network Congestion
____________ is defined as the reduced quality of service that occurs when a network node or link is carrying more data than it can handle.
Private Communication System
____________ is designed for limited number of subscribers
Switching
____________ is the provision of an on-demand connection between two end points.
Antonio Meucci
____________, a brilliant Italian inventor, filed the first one-year renewable notice of an impending patent of the "teletrofono" on December 28, 1871.
Interior gateway protocols type 2
____________, distance-vector routing protocols, such as Routing Information Protocol, RIPv2, IGRP.
Exterior gateway protocols
_____________ are routing protocols used on the Internet for exchanging routing information between Autonomous Systems, such as Border Gateway Protocol (BGP), Path Vector Routing Protocol.
Traffic engineering
_____________ is a method of optimizing the performance of a telecommunications network by dynamically analyzing, predicting and regulating the behavior of data transmitted over that network.
Circuit switching
_____________ is ubiquitous in the telephone network.
Telephone System
______________ is a two-way communication system
Telephone Communication System
______________ is designed so that it can connect to any telephone in the world (no compatibility needed) and regardless of distance (range of connection)
Switching network
______________ is the group of connections formed in the process of connecting inlets and outlets.
Traffic Engineering
______________ is the process of distributing traffic flows through the network to achieve load balancing
Call-Second, Call-Minute, Call-Hour
_______________ are units of traffic quantity representing the occupation of a circuit for a second, a minute, or an hour.
Circuit switching
_________________ provides a dedicated path between the two end points.
Alexander Graham Bell
_________________ recommended the Switching between the subscribers using a switching office that maintains the telephone connections.
switch
a device capable of creating temporary connections between two or more devices.
ringer
a device that converts electrical signal from the central office to an audible signal alerting the subscriber that he/she is being called
transport
actual transmission of voice
pulse dialing
also known as loop disconnect dialing, rotary or decadic dialing. The purpose is to set up a series of pulses of current in the telephone circuit.
Subscriber Line Interface Circuit
also known as the LINE SIDE INTERFACE
Switching System
also known as the Switching Office or the Exchange
Switching system
collection of switching elements arranged and controlled in such a way as to set up a common path between any two distant points.
trunk lines
connect switches
tandem office
connects COs without having any direction to the individual telephones
transport core
connects end office switches and core switches
local loop
connects the subscriber/PBX to the COs
transmission regulating unit
consists of a number of capacitors, varistors and resistors whose function is to maintain same speech level regardless of strength of received signals
Circuit-switched network
consists of a set of switches connected by physical links
Mesh and Star topology
conventional methods that connect devices in a network that are impractical and wasteful when the network becomes large
transmitter
converts acoustic energy into electrical energy by means of an input transducer
receiver
converts electrical signal into audible sound or signals, it consists of an output transducer
circuit-switched network
dedicated physical path from transmitter to receiver for the duration of the communication (PSTN)
Telephone Network
group of interconnected switches and subscribers
2007
iPhone debuts
nodes
in switched network, ___________ may be connected to end systems
routing
in switched network, nodes may be used for _______
Point of Presence
inter exchange carrier has its own connection to the local telephone system
Trunk Line
is a direct link between two telephone exchanges or switchboards that are a considerable distance apart
HYBRID
is a two-wire to four-wire circuit for simultaneous two-way conversation on a single pair of wires
CENTRAL OFFICE
it contains all the equipment that operates the telephone
Packet switching
it has started to proliferate into the telephone network under the asynchronous transfer mode (ATM) banner.
Equated Busy-Hour Call
it is a European unit of traffic intensity equal to 1/30 of an Erlang
Traffic engineering
it is the application of knowledge of statistics including queuing theory, the nature of traffic, their practical models, their measurements and simulations to make predictions and to plan telecommunication networks
on-hook condition
refers to a telephone which is not in use
Telephone Traffic
refers to the aggregate of all users' request being serviced by the network
off-hook condition
refers to the handset which is being taken out of the cradle
.Telecommunications
represent the transfer of information, from an entity at one place to an entity at another place, whereas the information can be in the form of data, voice or symbol.
central office
represented by a circle
PBX
represented by a rectangle
subscriber
represented by a triangle
packet-switched network
sends short bursts of data from point to point as needed
CODING
the CO must provide functions that converts Analog to Digital, and vice versa.
RINGING
the CO must provide ringing signal to a receiving station (90 Vrms signal AC at approximately 20 Hz)
BATTERY
the CO provides a DC voltage to the subscriber to operate the telephone. Usually -48 Vdc with resect to ground.
PSTN
the largest and probably the most important communication system in the world
Stored Program Control technology
the method of storing the programs on a processor or computer is called the ___________
Called Subscriber.
the one for whom the call is destined is the ____________
Calling Subscriber
the one who initiates the call is referred to as the ___________________
data transfer
the two parties can transfer data after the connection set-up
OVER-VOLTAGE PROTECTION
these are circuits and components that protect the SLIC from electrical damage
Circuit switching, Packet switching, Message switching
three method of switching:
connection tear down
when one of the parties need to disconnect, a signal is sent to each switch to release the resources
Switched
anyone can possibly communicate with anyone else
signaling
control of calling
ERLANG
it is the international dimensionless unit of traffic intensity.
Telecommunication
means the exchange of information between two distant places
Public Switched Telephone Network
PSTN
circuit-switching
Switching at the physical layer in the traditional telephone network uses the ______________ approach
PSTN
The _____________ can be defined as organizations and facilities involved in connecting a calling telephone to the called telephone regardless of where it might be.
Voice traffic
_________ is measured by the Erlang, which is the unit of (telephone) traffic intensity.
Interior gateway protocols type 1
____________ link-state routing protocols, such as OSPF and IS-IS
topology
basic structure of a local calling area or a typical switched telephone system
switched network
consists of a series of interlinked nodes
touch dialing
each digit is represented by a unique pair of tones
Erlang
named after Agner Krarup Erlang
BORSCHT
seven basic functions of an SLIC:
TEST SIGNALS
to check the status and quality of subscriber lines