Download New Latest (May) Cisco 642-427 Actual Tests 91-100

By | May 17, 2015

Ensurepass

 

QUESTION 91  (Topic 2)

 

 

How does the echo canceller interpret a signal when the ERL value is too low?

 

A.

The echo canceller treats the signal as echo and applies the configured values.

B.

The echo canceller considers the signal returning to the gateway as comfort noise generated during periods of silence and does not act on it.

C.

The echo canceller will apply the maximum echo-cancel coverage time to the signal to determine if this is echo or voice.

D.

The echo signal retuning to the gateway is too loud and the echo canceller interprets it as normal voice instead of echo.

 

Answer: D

Explanation:Insufficient echo return loss (ERL) to handle the echo might cause these problems:

Echo canceler does not cancel, but not enough to make echo inaudible. If the ERL value is too low, the total echo return loss seen by the IP network (ACOM) might be insufficient to suppress the echo. ERL needs to be approximately 20 dB (at least 15 dB) Echo canceler does not cancel.If the ERL value is too low, the echo signal that returns to the gateway might be too loud(within 6 dB of the talker signal). This causes the echo canceler to consider it as voice (double-talk) instead of echo. As a consequence, the echo canceler does not cancel it. ERL needs to be

approximately 6 dB or higher for the echo canceler to engage. In Cisco IOS Software Release 12.2.13T, you can configure this ERL level. See theEcho Canceler Enhancements in Cisco IOS Software Releases 12.2.11T and 12.2.13Tsection of this document. http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.s html

 

 

QUESTION 92  (Topic 2)

 

Refer to the exhibit. You have received a trouble ticket stating that calls to international numbers are failing. To place an international call, users dial the access code “9,” followed by “011,” the country code, and the destination number. After entering the debug isdn q931 command on the MGCP gateway, you have the user attempt the call again.

 

 

 

clip_image001

 

Based on the debug output, what is the most likely cause of this problem?

 

A.

Cisco Unified CallManager is not stripping the access code before sending the call to the gateway.

B.

The gateway dial peer needs to prefix “011” to the called number so the PSTN knows this is an international call.

C.

The user’s CSS does not permit international calls.

D.

The TON is incorrect.

E.

The circuit is not configured correctly or has a physical layer issue.

 

Answer: E

Explanation:This question is to test the troubleshooting of the call failure via the debug information. According to the debug information, the channel requested by the call is unavailable. There are two reasons:

1. The channels used by two endpoints are different;

2. Because of the configuration error, the connection cannot be established. Cause No. 44 – requested circuit/channel not available [Q.850] This cause is returned when the circuit or channel indicated by the requesting entitycannot be provided by the other side of the interface.

 

 

QUESTION 93  (Topic 2)

 

Your company has a centralized IP Telephony system and branch offices in eight major cities. The manager of your company help desk recently published local access numbers for external customers to reduce the costs associated with your company’s toll-free 800 service. However, when customers call the new local numbers they hear a reorder tone

 

 

instead of your centralized IVR.

 

What is the best solution to this issue?

 

A.

Deploy transcoders at each remote location.

B.

Deploy transcoders at the central location.

C.

Deploy Cisco Unified IP IVRs at each remote location.

D.

Increase the number of ports in the centralized IVR.

 

Answer: B

 

 

QUESTION 94  (Topic 2)

 

Which type of echo is found mostly on tail circuits and is due to reflection that causes the Tx signal to appear on the Rx signal?

 

A.

Hybrid echo

B.

Talker echo

C.

Listener echo

D.

Tail-end echo

 

Answer: A

Explanation:IntroductionThis document describes how to troubleshoot and eliminate echo where possible inIP Telephony networks with Cisco IOS?gateways.There are two sources of echo:* Hybrid echo* Acoustic echoHybrid echo is caused by an impedance mismatch in the hybrid circuit, such as atwo-wire to four-wire interface. This mismatch causes the Tx signal to appear onthe Rx signal.Acoustic echo is caused by poor acoustic isolation between the earpiece and themicrophone in handsets and hands-free devices.

 

 

QUESTION 95  (Topic 2)

 

You are troubleshooting why a user cannot make calls to the PSTN. You are reviewing trace files and you have found where the user’s IP phone initiates the call but you never see the call go out the gateway. What is the next step in troubleshooting this issue?

 

A.

Look in the SDL trace file to see if there is a signal to another Cisco Unified CallManager node with the same time-stamp.

B.

Look in the SDL trace file to see if there is a signal to another Cisco Unified CallManager node with the same TCP handle.

C.

Look in the IP Voice Media Streaming App trace file to see if an MTP was invoked.

D.

Look in the MGCP trace file to determine which MGCP gateway the call was sent to.

 

Answer: A

 

 

QUESTION 96  (Topic 2)

 

Echo is always present to some extent in all voice networks. For echo to be a problem, which three conditions must exist? (Choose three.)

 

A.

analog leakage between analog Tx and Rx paths

B.

sufficient echo amplitude to be perceived as annoying

C.

sufficient power from the talker’s side to cause listener echo

D.

sufficient delay in echo return for echo to be perceived as annoying

E.

an analog two-wire to four-wire hybrid operating below 600 ohm impedance

 

Answer: ABD

Explanation:Echo is perceived as annoying when all of these conditions are true:

Signal leakagebetween the analog Tx and Rx paths.

Sufficientdelayin echo return.

Sufficientecho amplitude.

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.s html

 

 

QUESTION 97  (Topic 2)

 

Refer to the exhibit. You have received a trouble ticket stating that users cannot place calls to the PSTN. During testing you discover the gateway is not switching to the secondary call agent when the primary call agent is unreachable.

 

What needs to be done to allow the MGCP gateway to use a different call agent if the primary fails?

 

 

 

clip_image002

 

A.

The ccm-manager fallback-mgcp command needs to be added to the gateway.

B.

The ccm-manager redundant-host command needs to be added to the gateway.

C.

A Cisco Unified CallManager group that includes the secondary call agent needs to be assigned to the gateway.

D.

The gateway needs to be defined as a non-gatekeeper-controlled intercluster trunk with the secondary Cisco Unified CallManager defined.

 

Answer: B

 

 

QUESTION 98  (Topic 2)

 

Refer to the exhibit. A site is using four-digit extensions for internal calling. The voice-mail pilot number is 8000. Calls to extension 2001 hear the Cisco Unity opening greeting instead of the subscriber’s greeting when forwarded to Cisco Unity.

 

What is the probable cause?

 

clip_image003

 

A.

The mailbox is configured with the E.164 number instead of the extension.

B.

A call routing rule has been added that is preempting the Attempt Forward rule.

C.

Extension 2001 has not been defined in Cisco Unity.

D.

A greeting has not been recorded for mailbox 2001.

E.

The Voice Mail Box Mask setting in Cisco Unified CallManager is set to 8000 instead of XXXX

 

Answer: E

 

 

QUESTION 99  (Topic 2)

 

Refer to the exhibit. A user at BR1 is on a call to the PSTN through the PRI interface on the local H.323 gateway. The IP WAN has just failed and the call has been dropped.

 

clip_image004

 

What is causing the call to be dropped?

 

A.

The H.323 gateway has lost the D channel on the PRI.

B.

SRST hasn’t been configured on the BR1 gateway.

C.

The no h225 timeout keepalive command has not been configured on the gateway.

D.

The IP phone hasn’t registered with SRST.

 

Answer: C

 

 

QUESTION 100

HOTSPOT  (Topic 2)

 

 

 

clip_image005

Answer:

clip_image006

 

A.

 

B.

 

C.

 

D.

 

 

Answer:

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