Voice Systems Flashcards

What is the primary purpose of a dial plan in a PBX or IP-PBX system?

Answer: Specify rules for routing calls based on dialed digits

A dial plan defines the rules that a PBX uses to interpret dialed digit strings and route calls to the appropriate destination.

Which type of VoIP gateway converts calls between the analog PSTN and a SIP-based IP network?

Answer: Media gateway

A media gateway performs the conversion between circuit-switched PSTN signals and packet-switched VoIP protocols such as SIP.

What does QoS DSCP marking AF41 indicate for VoIP traffic?

Answer: Assured Forwarding class 4, drop probability 1 — high priority multimedia

DSCP AF41 (Assured Forwarding 41) indicates Class 4, low drop precedence, typically used for interactive video and high-priority multimedia traffic.

A hunt group is configured with a 'linear' (top-down) hunting method. Which phone rings first?

Answer: The first phone in the list, every time

In linear hunting, the system always starts at the first agent in the list and works down, meaning the first phone rings on every new call if it is available.

Which cable category is the minimum recommended for deploying PoE-powered IP phones to avoid excessive heat buildup?

Answer: Cat 6

Cat 6 cable is recommended for PoE applications because its larger conductors produce less resistance and less heat under the current loads used by PoE devices.

What is the function of a Session Border Controller (SBC) in a VoIP network?

Answer: Control and secure signaling and media at the network border

An SBC sits at the edge of a VoIP network to enforce security policies, perform NAT traversal, and control signaling and media flows between networks.

When testing an analog voice line with a butt set, the technician places it in 'monitor' mode. What does this allow?

Answer: Listen to the line without interrupting an active call

Monitor mode on a butt set allows the technician to bridge across the line and listen in on an active call without interrupting it.