Dial Peers

Here you will find answers to CVoice – Dial Peer Questions

Question 1

Refer to the exhibit. You have been asked to configure a dial peer on R2 that will match only the extensions of the four telephones attached. Which dial-peer statement will you use?

A. dial-peer voice 1 pots
destination-pattern 5552.[0-5]0
B. dial-peer voice 1 pots
destination pattern 5552[5-6].0
C. dial-peer voice 1 pots
destination-pattern 555[2-5][56]
D. dial-peer voice 1 pots
destination-pattern 5552[5-6][05]0

Answer: D

Explanation

The numbers can be summaried as 5552(5 or 6)(5 or 0)0 so the destination-pattern should be written as 5552[5-6][05]0 or 5552[56][05]0

Question 2

Refer to the exhibit. When extension 201-555-1000 dials 404-555-1200, how are the digits manipulated in R1 so that they are presented correctly at R2?

hostname R1 ! interface serial 0/0 ip address 172.16.1.1 255.255.255.248 ! controller t1 framing esf clock source line lincode b8zs ds0-group timeslots 1-24 type e&m-wink-start ! voice-port 1/0:1 ! dial-peer voice 1 voip destination-pattern 404555…. session-target ipv4:172.16.1.6 ! dial-peer voice 2 pots destination-pattern 201555…. port 1/0:1

hostname R2 ! interface serial0/0 ip address 172.16.1.6 255.255.255.248 ! controller t1 framing esf clock source line lincode b8zs ds0-group timeslots 1-24 type e&m-wink-start ! voice-port 1/0:1 ! dial-peer voice 1 voip destination-pattern 201555…. session-target ipv4:172.16.1.1 ! dial-peer voice 2 pots destination-pattern 404555…. port 1/0:1

A. The outbound VoIP dial peer is matched and all digits are sent.
B. The digits 404-555 are stripped off before matching the outbound POTS dial peer.
C. The digits 404-555 are stripped off by the connection trunk and R2 receives only 1200.
D. R1 collects the 1200 and prepends the tie-line digits 404555. That number is matched to a VoIP dial peer and sent to the appropriate address.

Answer: A

Explanation

When 201-555-1000 (Phone A) calls 404-555-1200 (Phone B) the dial-peer voice 1 voip at R1 is matched with the destination-pattern 404555…. But notice that this is a voip dial-peer so digits are not stripped and all digits are sent to R2.

Question 3

Refer to the exhibit. Your customer wants to converge the existing PBX network with the IP network. The three remote offices have various types of PBXs. The customer is using a combination of tie-lines and trunks to connect the PBXs today. Which kind of connection should be implemented to allow calls to be placed from 201-555-1000 to 727-555-1000 so that when the call is completed, network resources are returned for other uses?

A. PLAR
B. trunk
C. tie-line
D. answer-mode

Answer: C

Explanation

E&M signaling supports tie-line type facilities.

Question 4

Which dial plan characteristic shows the most obvious improvement by dropping a number translation step?

A. availability
B. post-dial delay
C. scalability
D. hierarchical design

Answer: B

Explanation

Post-dial delay is the time between when the last digit is dialed and the moment the phone rings at the receiving location. In the PSTN, people expect a short post dial delay and to hear ring back within seconds. The more translations, digit manipulations, and lookups that take place, the longer the post dial delay becomes. Overall network design, translation rules, and alternate paths affect post dial delay. Minimize the amount of dial peers and translations to reduce post-dial delay.

By dropping a number translation step, the post-dial delay time will be obvious improvement.

Question 5

Refer to the exhibit. Users are not able to complete a call from 678-555-1212 to 770-555-1111. What is the correct diagnosis for the problem?

A. incorrect destination-pattern in router 1
B. incorrect POTS dial-peer statement in router 2
C. incorrect session-target statement in router 2
D. incorrect port statement in router 1 pots dial peer
E. missing no digit-strip on the voip dial peer in router 1

Answer: A

Explanation

The dial-peer 2 voip in Router 1 was configured “destination-pattern 770555..”. Notice that there are only two dots (.) in the destination-pattern that means when the user presses 77055511, the voip dial-peer is matched immediately without waiting for two last “11” pressed. Therefore router R2 only receives the “777055511” number and it doesn’t match with the destination-pattern in the “dial-peer voice 1 pots” configured in router R2.

Question 6

Refer to the exhibit. Three department managers share the directory number 3000. The Marketing manager’s phone is attached to port 1/1. The Engineering manager’s phone is attached to port 1/2. The Shipping manager’s phone is attached to port 1/3. In which situation would an incoming call ring on the Shipping manager’s phone?

dial-peer voice 1 pots destination pattern 3000 port 1/1 preference 0 ! dial-peer voice 2 pots destination pattern 3000 port 1/2 preference 1 ! dial-peer voice 3 pots destination pattern 3000 port 1/3 preference 2

A. The Marketing manager is on the phone.
B. None of the managers are on the phone.
C. The Engineering manager is on the phone.
D. The Shipping manager and Marketing manager are on the phone.
E. The Engineering manager and Marketing manager are on the phone.

Answer: E

Explanation

With the preference 0 configured in dial-peer voice 1 pots, this dial-peer (Marketing) has the highest priority to receive call if it is idle. Dial-peer 2 (Engineering) has the next priority and dial-peer 3 (Shipping) has lowest priority so it only rings when both Marketing and Engineering phones are busy.

It is a bit weird but the router considers lower preferences to be better than higher preferences. One more notice is that the default preference for a dial peer is 0.

Question 7

Refer to the exhibit. Your customers dial in to your company using a local number, and their calls cross the WAN to an IVR system. They are complaining that the IVR system does not always accept their input or may get it wrong. The IVR system has been checked and is working properly. What needs to be added to the dial peer on the incoming H.323 gateway to correct this problem?

dial-peer 100 voip destination-pattern …1111 session target ipv4:10.1.1.1 codec g729ar8

A. no vad
B. tech-prefix 1#
C. codec g729ar8 bytes 30
D. dtmf-relay h245-alphanumeric

Answer: D

Explanation

DTMF is the tone generated when you press a button on a touch-tone phone. This tone is compressed at one end of a call; when the tone is decompressed at the other end, it can become distorted, depending on the codec used. The DTMF relay feature transports DTMF tones generated after call establishment out-of-band by using either a standard H.323 out-of-band method or a proprietary RTP-based mechanism. For session initiation protocol (SIP) calls, the most appropriate method to transport DTMF tones is Real-Time Transport Protocol named telephony event (RTP-NTE) or session initiation protocol notify (SIP Notify).

When you press a button on the touch-tone phone, a “high group” frequency is combined with a “low group” frequency and you can hear a generated tone. Notice that you often don’t see the “A B C D” column in most modern DTMF phones nowadays.

Although DTMF is usually transported accurately when using high-bit-rate voice codecs such as G.711, low-bit-rate codecs such as G.729 and G.723.1 are highly optimized for voice patterns and tend to distort DTMF tones. As a result, interactive voice response (IVR) systems may not correctly recognize the tones. Therefore the IVR sometimes can not recognize the DTMF tones and doesn’t accept their input o may get it wrong.

The main advantage of the “dtmf-relay” command is it sends DTMF tones with greater fidelity than is possible in-band for most low-bandwidth codecs, such as G.729 and G.723.

(Reference: CVoice Student Guide v6.0)

Question 8

You have designed a complex dial plan using digit manipulation. Given the following snippet of your configuration file, what action would you expect to result when a call beginning with the digits “612” is received?

dial-peer voice 1 pots destination-pattern 612….. no digit-strip prefix 5501 port 1/0/0

A. A nine digit number beginning with 5501 will be forwarded.
B. A ten digit number beginning with 5501 will be forwarded.
C. A twelve digit number beginning with 5501612 will be forwarded.
D. A thirteen digit number beginning with 5501612 will be forwarded.

Answer: C

Explanation

This dial-peer has the “no digit-strip” command so no digits are stripped when this dial-peer is matched. So the whole number will be transferred with the format of 5501612xxxxx (5501 is prefixed with the command prefix 5501)

Question 9

Which command sets parameters to search a series of dial peers for a destination that is not in use?

A. dial-peer rotary
B. dial-peer circulate
C. dial-peer hunt
D. dial-peer distribute

Answer: C

Explanation

Dial peer hunting is the process used when an originating router tries to establish a call on different dial peers if the originating router receives a user-busy invalid number or an unassigned-number disconnect cause code from a destination router.

Question 10

On the basis of the provided exhibit. Enzo’s Bikes manufactures high end bicycle frames. Until recently they sold only to bicycle shops; however, now they are starting to sell to end users. They need a way to add two additional sales staff and ensure that the senior sales technician always gets the first call. Drew is the senior sales technician. Bob is the newest sales technician. Bob’s phone should always be the last one chosen for incoming sales calls, after Drew and James. Bob’s phone should be chosen first only when Drew and James are busy on calls. Select the correct dial-peer command set for Bob’s phone.

A.
dial-peer voice 3 pots
destination-pattern 5555110
preference 2

B.
dial-peer voice 3 pots
destination-pattern 5555110
preference firstlast

C.
dial-peer voice 3 pots
destination-pattern 5555110
preference 0

D.
dial-peer voice 3 pots
destination-pattern 5555110
preference high

Answer: A

Explanation

The router considers lower preferences to be better than higher preferences and the default preference is 0. Therefore, by setting the preference of Bob’s dial-peer to 2 we guarantee Bob will be the last one to receive the call (while James’ priority is set to 1 and Drew uses the default configuration).