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CTY L6 Review > VoIP Midterm > Flashcards

VoIP Midterm Flashcards

General overview of key topics leading up to midterms

1
Q

What is POTS?

A

Plain old telephone service/system (analog over copper loops)

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2
Q

What is DTMF?

A

Dual-Tone Multi-Frequency (2 frequencies for one tone value)

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3
Q

What is PSTN?

A

Public Switched Telephone Network (world’s circuit-switched telephone networks, using a reserved consistent path for signals allocated on call)

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4
Q

What is ISDN?

A

Integrated Services Digital Network

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5
Q

What makes up an ISDN?

A

Copper wires using TDM, virtual out of band control channel (D channel) and virtual data channels (B channels)

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6
Q

What are the 2 varieties of ISDN?

A

Basic Rate (BRI) and Primary Rate (PRI)

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7
Q

What does BRI consist of?

A

2 B channels (128kBps) and 1 D channel

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8
Q

What does PRI consist of?

A

T1 and 23 B channels

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9
Q

What is KTS?

A

Key Telephone System

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10
Q

What is PBX?

A

Private Branch Exchange

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11
Q

What are properties of KTS?

A

Hard wired, shared lines, for small business

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12
Q

What are properties of PBX?

A

Line cards (LAN), trunk cards (WAN), control cards (routers/switches)

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13
Q

What is VoIP?

A

Voice over IP, audio technology allowing voice communication to be encapsulated into binary packets for an IP network

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14
Q

What is UC?

A

Unified Communications; a set of products and the ability to unify multiple modes of communication under a single network.

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15
Q

What are the steps to Voice Encoding?

A
  1. Sample the analog signal
  2. Quantize the sample
  3. Encode the digital signal
  4. Compress the samples to reduce bandwidth
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16
Q

What is the Nyquist Theorem?

A

Sampling rate has to be at least twice the maximum frequency. It determines the minimum sampling rate of analog signals.

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17
Q

What is Quantization?

A

The representation of amplitudes by a certain value (step) where samples are rounded up/down to the closer step

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18
Q

What is Quantization Noise?

A

The inexactness from quantization.

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19
Q

What is the result of Linear Quantization?

A

Higher SNR on large signals is better quality, lower SNR on small signals is worse quality.

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20
Q

What is Logarithmic Quantization?

A

The reduction in step size (higher granularity) at lower signals to provide uniform SNR for all signals.

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21
Q

What is SNR?

A

Signal-to-noise ratio

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22
Q

What is a DSP?

A

Digital Signal Processor, an ASIC used for telephony applications at voice endpoints and can also be used for audio conferencing and transcoding

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23
Q

What is an ASIC?

A

An Application Specific Integrated Circuit

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24
Q

What is RTP?

A

Real Time Protocol, built on UDP and offers all the functionality required by voice packets

25
Q

What is RTCP?

A

Real Time Transport Control Protocol, based on periodic transmissions of control packets

26
Q

How is voice encapsulated?

A

In small packets at high packet rates

27
Q

What does Cisco’s UC strategy consist of?

A

On-premises call control and UC applications

28
Q

What is CME?

A

Cisco Unified Communications Manager Express; VoIP management application which runs on an Integrated Services Router’s (ISR) Internetworking Operating System (IOS)

29
Q

What functions does CME provide?

A

Call processing, dial plan administration, phone feature administration, directory services, gateway features and modules

30
Q

What is CUCM?

A

Cisco Unified Communications Manager

31
Q

What are examples of Cisco soft clients?

A

Jabber and WebEx

32
Q

What features are required for IP telephony networks?

A 
PoE
CDP/LLDP/Voice VLAN
DHCP server
TFTP server
NTP server
33
Q

What telephony protocols are used in VoIP communication?

A

Gatekeeper for call control, most common signaling is SIP, after setup uses RTP

34
Q

What is SIP?

A

Session Initiation Protocol; designed to create, modify, and terminate a session over IP

35
Q

What are the 6 core methods used by SIP?

A 
INVITE
BYE
REGISTER
CANCEL
ACK
OPTIONS
36
Q

What is the IP phone startup process?

A
  1. Obtain PoE
  2. Learns VLAN information from CDP/LLDP
  3. Requests IP from DHCP server
  4. Receives DHCP IP configuration
  5. Downloads Device Configuration File
  6. Registers with gatekeeper
  7. Gatekeeper responds with SIP 200OK
37
Q

What are the 3 tasks to prepare CME to support Cisco IP phones?

A
  1. Configure the ISR to act as a TFTP server
  2. Initial CME configuration - ISR voice services
  3. Configure and generate phone configuration files
38
Q

What are the 3 mandatory SIP configuration steps?

A
  1. Configure SIP VoIP services on ISR
  2. Configure the source IP
  3. Configure the maximum number of endpoints and DNs allowed on the CME
39
Q

What is a Voice Register Pool?

A

CME endpoints (IP phone)

40
Q

What is a Directory Number (DN)?

A

The virtual phone line associated with the voice register pool

41
Q

What does the Restart command do?

A

Performs a quick reset and updates DNs, phone buttons, speed dials

42
Q

What does the Reset command do?

A

Performs a full boot and updates Date/Time, phone firmware, CUCME source IP, TFTP download path, voice mail access number in addition to restart info

43
Q

What are the features of CME?

A

Softkey speed dials
Call forwarding
Hunt groups
Voice Hunt groups

44
Q

What is an outside line?

A

A direct connection to the telephone line outside of the building, aka POTS line. With all phones on-hook, voltage should measure around 48V DC. To ring, applies a 90VAC signal.

45
Q

What are the 3 types of Analog Voice Ports?

A

Supervisory signaling, Address signaling, Information signaling

46
Q

What is Supervisory signaling?

A

Loop-start or ground-start

47
Q

What is Address signaling?

A

Pulse or DTMF

48
Q

What is Information signaling?

A

Call progression tones

49
Q

What are the types of interfaces that Gateways use to connect to non-IP devices?

A

Analog phones, fax, non-IP PBX, PSTN switches (CO)

50
Q

What are examples of analog interfaces?

A

Foreign Exchange Station/Office (FXS/FXO)

51
Q

What are examples of digital interfaces?

A

T1 (CAS,CCS) and E1 (CAS,CCS)

52
Q

What are the 4 call types?

A

Local - doesn’t traverse WAN/PSTN
On-net - Between two phones on the same data network
Off-net - When a user dials an access code to access the PSTN
PLAR - automatic connection

53
Q

What is a call leg?

A

A logical connection between two routers or between a router and a telephony device (hop) which is router-centric (only worried about next hop)

54
Q

What is a Dial Peer?

A

An addressable call endpoint which establishes call legs to complete an end-to-end call

55
Q

What are the 2 types of dial peers?

A

POTS dial peers, VoIP dial peers

56
Q

What are POTS dial peers?

A

Traditional telephony network connection that match calls to voice ports.

57
Q

What are VoIP dial peers?

A

Packet switched network connection that match calls to session targets (IP address or DNS name).

58
Q

What happens when voice register dn is configured with a number (destination pattern)?

A

A voice dial-peer is automatically created.

59
Q

What type of dial-peer will strip any digits that match the destination pattern before routing a call?

A

POTS dial-peer

CTY L6 Review (4 decks)

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