Topic 4 – PSTN and Service Provider Networks

Question 11
You are CCNA VOICE associate in Lead2pass.com. When would you require a voice gateway? (Choose two.)
A.When you connect a branch location to IP WAN
B.When you connect a branch location using VoIP to the PSTN
C.When you connect a Cisco Unified Communications Manager to a LAN
D.When you connect a Cisco Unified Communications network to a PBX
Answer: B D

Explanation:
This question tests the function of voice gateway.
There are there functions of voice gateway:
1. Medium Translation;
2. Signaling Translation;
3. Media Translation;
A voice gateway is generally used to connect the traditional communication network and IP communication network. Thus, the correct answers are B and D.

Question 12
Identify two gateway supplementary services. (Choose 2.)
A.Hold
B.DTMF relay
C.Transfer
D.Transcoding
Answer: A C
There are many kinds of supplementary services, such as Call Hold, Call Forwarding, Call Transfer, Call Pickup, Conferencing, etc. All supplementary services work internally, but when a g729 call is established with IP Phone, none of the supplementary service works.

Question 13
You are CCNA VOICE associate in Lead2pass.com.Pleaes point out three components of a dial plan. (Choose three.)
A.endpoint protocol
B.endpoint addressing
C.digit manipulation
D.call coverage
Answer: B C D
Explanation:
The dial plan is one of the key elements of a Unified Communications system, and an integral part of all call processing agents. Generally, the dial plan is responsible for instructing the call processing agent on how to route calls. Specifically, the dial plan performs the following main functions:
Endpoint addressing: Reachability of internal destinations is provided by assigning directory numbers (DNs) to all endpoints;
Path selection: Depending on the calling device, different paths can be selected to reach the same destination;
Calling privileges: Different groups of devices can be assigned to different classes of service, by granting or denying access to certain destinations;
Digit manipulation: In some cases, it is necessary to manipulate the dialed string before routing the call;
Call coverage: Special groups of devices can be created to handle incoming calls for a certain service according to different rules (top-down, circular hunt, longest idle, or broadcast).

Question 14
You are CCNA VOICE associate in Lead2pass.com. You need configure a voice port that will terminate a loop or ground start line from the PSTN or a PBX. Which type of voice port you will configure?
A.FXO
B.FXS/FXO   
C.PRI T1/E1
D.BRI
Answer: B
Explanation:
A device that connects to a telephone interface contains a Foreign exchange office (FXO) interface and could be a standard analog telephone or a private branch exchange (PBX) to receive telephone service. The FXS/FXO will terminate a loop or ground start line from the PSTN or a PBX.

Question 15
A call leg is a virtual connection that is set up and torn down before the dial peer is established.
A.TRUE
B.FALSE
Answer: B
Explanation:
This question is to examine the relationship between the call leg and dial-peer.
Both dial-peer and call leg are logical connections. The equivalence condition of two dial-peers is able to negotiate via dial-peer. The established virtual connection after successful negotiation is called call leg. Choose B.