Cvoice 1 - Traditional Telephony

Front 1

- What are the 2 types of edges devices used in a telephony network?

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Back 1

- Analog telephone and Digital telephones (it’s an edge devices because it terminates the service provided by the local telephone company)

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Front 2

- What is the local loop?

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Back 2

- It is the interface to the telephone company network (It’s the pair of wires that come to your house to provide residential telephone service.)

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Front 3

- The CO switch is used for what?

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Back 3

- Used to terminate local loop
- Handle signaling,
- Digit collection
- Initial call routing decision
- Call setup
- Call teardown


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Front 4

- What is the primary function of a Trunk?

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Back 4

- It’s to provide the path between 2 switches

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Front 5

- What is a Tie trunk?

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Back 5

- A dedicated circuit that connects PBX directly

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Front 6

- What is a CO trunk?

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Back 6

- A direct connection between a local CO and a PBX.

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Front 7

- What is an interoffice trunk?

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Back 7

- A circuit that connects two local telephone company COs

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Front 8

- The CO makes the telephone work with 5 components?

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Back 8

- Battery
- Current detector
- Dial- generator
- Dial register.
- Ring generator


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Front 9

- Switching systems provide 3 primary functions?

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Back 9

- Call setup, routing and teardown
- Call supervision
- Customer ID and telephone numbers.


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Front 10

- What is a PBX?

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Back 10

- The private branch exchange is a smaller version of the CO switches used by telephone companies. It’s connected to the telephone handset using a line card and to the local exchange using a trunk card.

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Front 11

- What are the 3 majors components of a PBX?

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Back 11

- Terminal interface
- Switching network
- Control complex


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Front 12

- The key system (not a switch unlike the PBX) is an alternative to the PBX, mostly used in office with 30 to 40 users, what are the 3 major components?

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Back 12

- Key service unit.
- System software
- Telephones


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Front 13

- What is the main difference between a key system and a hybrid telephone system?

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Back 13

- The main difference is whether a single-line telephone can access a single CO local loop or trunk only (key telephone system),

or whether the single-line telephone can access a pool of CO local loop or trunk (hybrid telephone system.

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Front 14

- What is call signaling?

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Back 14

- It’s the capacity of a user to communicate a need for service to a network

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Front 15

- What are the 3 types of call signaling? (Note; all 3 types must be carried across both analog and digital connections.)

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Back 15

- Supervisory; a subscriber and telephone company notify each other of calls status with audible tones and exchange of electrical current.

- Address signaling; (DTMF or Pulse)

- Informational signaling; (Tone combination indicates call progress; Busy, Ring back, Congestion..etc)


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Front 16

- What are the 3 majors steps in an end-to-end call?

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Back 16

- Local signaling – originating side: User signal the switch by going off hook

- Network signaling: switch makes a routing decision

- Local signaling – terminating side: signal to the call recipient


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Front 17

- What are the 3 types of supervisory signaling

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Back 17

- On hook
- Off hook
- Ringing


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Front 18

- What are the 2 types of address signaling used to notify the telephone company?

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Back 18

- DTMF; each button associated with low and high frequencies are pressed to notify the telephone company of the number being dialed.

- Pulse; large numerical dial wheel.

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Front 19

- Name 3 types of digital connections used for PBX connections (that is the connection between the PBX and the switch – or network)

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Back 19

- T1 (hold the CAS – in band)
- E1 (hold the CAS – out of band)
- PRI/BRI (hold the CCS)


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Front 20

- What is CAS (carried by a T1 or E1 in a digital PBX connection to the network)

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Back 20

- CAS = Channel associated signaling
- Method that allows passing on-hook or off-hook status by setting bits that are associated with each specific voice channel.


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Front 21

- What is “ out of band “ signaling?

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Back 21

- The signaling and the voice path and do not share the same channel.

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Front 22

- What is the channel used by an ISDN connection to carry the signaling messages for all other channels?

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Back 22

- The D channel.

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Front 23

- All 3 types of call signaling are used when you place a phone call from home. Can you explain how?
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Back 23

- When the handset is lifted – this notifies the telephone company (that’s supervisory signaling)

- When the telephone company sends you the dial tone (that’s informational signaling)

- When you dial the digits by pressing numbers (that’s address signaling)


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Front 24

- Multiplexing techniques have been implemented for what?

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Back 24

- The make better use of 2 wire or 4 wire connections in order to carry multiple conversation at the same time.

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Front 25

- List and describe 2 multiplexing techniques

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Back 25

- TDM; Time-Division Multiplexing = used extensively in telephony networks to carry multiple conversions concurrently across a four-wire path. Used in digital connections

- FDM; Frequency-Division Multiplexing = involves carrying multiple voice signals by allocating an individual frequency range for each call. Mostly used in analog connections- cable or DSL (digital subscriber line) to allow simultaneous use of multiple channels over the same wire.


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Front 26

- DSL is an example of which style of multiplexing?

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Back 26

- Frequency-division

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Front 27

- Which multiplexing technique is used by TDM?

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Back 27

- Timeslots are assigned to different channels, regardless of whether there is data to transmit.

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Front 28

- How does CAS pass signaling?

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Back 28

- In the same channel as voice for T1

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Front 29

- What type of signaling is “signaling that uses either pulse or DTMF”?

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Back 29

- Address signaling

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Front 30

- What type of signaling is “signaling that provides call-progress indicators to the initiator of a call“?

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Back 30

- Informational signaling

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Front 31

- What type of signaling is “signaling that monitors on-hook/off-hook transitions and provides call notifications “?

Back 31

- Supervisory signaling

Front 32

- At what point is the dial tone generated?

Back 32

- When the digits register is ready

Front 33

- Which type of trunk connects two local telephone company COs?

Back 33

- Interoffice trunk