642-425 IP Telephony Troubleshooting

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Question 1

You have recently installed a new Catalyst 3524-PWR switch in an IDF to increase the
number of IP phones for a department. The IP phone for an office receives power but
cannot communicate with the CallManager. The department uses VLAN 16 for data and
VLAN 160 for voice. From the given show running-configuration command there are
multiple problems. How can the communication problem with the CallManager be
resolved?
Dept16SW2#show running-configuration
output omitted
interface FastEthernet 0/6
switchport trunk encapsulation dot1q
switchport trunk native vlan 16
switchport mode trunk
switchport voice vlan 169
spanning-tree uplinkfast
switchport priority extend none
end

  • A. Change the voice VLAN to 160.
  • B. Change the switchport trunk encapsulation type to ISL.
  • C. Configure the port as an uplink to another switch configured for uplinkfast.
  • D. Change the incorrect switchport priority extend none command to switchport priority extend trust to extend the trust boundary to the IP phone.


Answer : A

Question 2

Use the diagram to assist in answering this question.
You have received a trouble ticket for a recently installed MGCP gateway. In testing it
appears that the CallManager cluster cannot communicate with the gateway. The gateway
address is 10.1.44.12/24 and the CallManager that is going to control the gateway has an
address of 10.1.44.4/24. Use the following configuration snip to resolve the problem.
mgcp
mgcp call-agent 10.1.44.4 2427 service-type mgcp version 1.0
mgcp dtmf-relay voip codec all mode out-of-band
mgcp rtp unreachable timeout 1000 action notify
mgcp modem passthroughvoice mode cisco
mgcp sdp simple mgcp package-capability rtp-package
mgcp package-capability sst-package no mgcp timer receive-rtcp
no mgcp explicit hookstate
ccm-manager config server 10.1.44.7
ccm-manager config
What command is missing from the configuration that will allow the CallManager to control
this gateway?


  • A. ccm-manager mgcp
  • B. mgcp bind control source-interface FastEthernet 0/0
  • C. ccm-manager redundant-host
  • D. ccm-manager fallback-mgcp
  • E. ccm-manager switchback


Answer : A

Question 3

Dept16SW4#show running-configuration
snip
interface FastEthernet 0/1
port group 1
interface FastEthernet 0/2
port group 2
interface FastEthernet 0/3
switchport trunk encapsulation dot1q
switchport trunk native vlan 16
switchport mode trunk
switchport voice vlan 160
spanning-tree portfast
switchport priority extend trust
!
end
Dept16SW4#vlan database
Dept16SW4(vlan)# show
VLAN ISL Id: 1
Name: default
Media Type: Ethernet
VLAN 802.10 Id: 100001
State: Operational
MTU: 1500
VLAN ISL Id: 16
Name: default
Media Type: Ethernet
VLAN 802.10 Id: 100016
State: Operational
MTU: 1500
You have installed a new Catalyst 3524-PWR to support a small group of IP telephony
users in Department 16. When the IP phones are tested they receive power, but do not
communicate with the CallManager. The above show interface FastEthernet 0/3 and show
VLAN database. What is the problem?

  • A. The VLAN and trunk statements are missing from FastEthernet ports 0/1 and 0/2.
  • B. VLAN 160 needs to be entered into the VLAN database.
  • C. Fast EtherChannel is supported on only the last four ports in a Catalyst 3524-PWR.
  • D. VLAN 16 is an 802.1q trunk and not an ISL trunk.


Answer : B

Question 4

Your company has recently installed Cisco Unity to be the voice mail platform for your
Cisco CallManager IP telephony system. You have received complaints from the users that
the red message waiting indicator (MWI) light does not come on when there are new voice
mail messages in the voice mailboxes. What must be verified and possibly modified to
resolve this issue? (Choose two.)

  • A. Use the Port Usage tool to verify that the ports dedicated to MWI on/off are not over- utilized. Add another dedicated port if the current port is over-utilized.
  • B. Verify that the MWI on/off numbers are unique within the CallManager cluster dial plan. If they are not, change the directory numbers in the CallManager cluster so they are unique and configure the Cisco Unity server so they match the new directory numbers.
  • C. Verify that the same directory numbers are being used for MWI on/off in both the Cisco CallManager cluster and Cisco Unity server. If they are different, change the Cisco Unity server to match the Cisco CallManager cluster
  • D. Verify the number of ports licensed for the Cisco Unity server is equal to the number of configured ports. If the number of configured ports is greater than the license number, reduce the number of configured ports to be no greater than the license number.
  • E. Verify that the calls are being sent to the correct ports on the Cisco Unity server. If they are incorrect on the Cisco CallManager cluster, change the values on the cluster to be correct.


Answer : B,C

Question 5

During a troubleshooting session, a router's access list is eliminated as a possible problem.
Which step in the Cisco Problem Solving Model does this represent?

  • A. implementing an action plan
  • B. defining the problem
  • C. gathering facts
  • D. considering possibilities


Answer : D

Question 6

You have recently installed IP Phones in a centralized model. At a remote branch using an
H.323 gateway, users are complaining they cannot call some internal numbers. After
dialing the last digit, they get a reorder tone. What is the most likely cause?

  • A. Partition/CSS configuration issue
  • B. Gateway dial-peer configuration issue
  • C. Codec mismatch
  • D. Call Admission Control


Answer : C

Question 7

Which CTI device allows only a single media stream at a time?

  • A. hunt group
  • B. route point
  • C. peer
  • D. port


Answer : D

Question 8

You have received a trouble ticket that an executive cannot retrieve his account information
from his bank. When the call is answered, the executive is prompted to enter his account
code. The bank does not seem to recognize the DTMF tones and disconnects the call.
What is a possible solution to this problem?

  • A. Configure progress_ind setup enable 3 under the gateway VoIP dial-peer.
  • B. Configure progress_ind alert enable 8 under the gateway POTS dial-peer.
  • C. Configure voice rtp send-rcv in the gateway.
  • D. Set CallManager Service Parameter ToSendH225UserInfoMsg to True.


Answer : C

Question 9

A phone has stopped working. Given the Event Viewer output shown, what is the most
likely problem?


  • A. The switch has improperly extended the trust boundary.
  • B. The phone went off-hook.
  • C. The phone does not have the proper DN.
  • D. The switch port to the phone was shutdown.


Answer : D

Question 10

The Event Viewer Application Log on the Cisco CallManager subscriber initially showed
device SEP000F223984410 unregistered with a Reason Code of 9. It is now registered
back to the Cisco CallManager subscriber. What was the possible cause?

  • A. The IP phone lost its keepalive after 90 seconds.
  • B. The Catalyst switch reset.
  • C. The device name was unknown.
  • D. The Cisco CallManager initiated a reset.


Answer : D

Question 11

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. an analog 2-wire to 4-wire hybrid operating below a 600 ohm impedance
  • B. analog leakage between analog Tx and Rx paths
  • C. sufficient delay in echo return for echo to be perceived as annoying
  • D. sufficient echo amplitude to be perceived as annoying
  • E. sufficient power from the talker's side to cause listener echo


Answer : B,C,D

Question 12

Hotspot





Answer :

Question 13

Phone users are complaining of delayed dial tones. What tool may be used to exhibit
resource utilization on the Cisco CallManager server?

  • A. Performance Monitor
  • B. Event Viewer
  • C. Log Viewer
  • D. Real-Time Monitor


Answer : A

Question 14

You have received a trouble ticket from an employee. The employee is reporting that he
can call his manager but his manager cannot call him. The employee is calling from
extension 2003 at site 2. His manager is at extension 2002 in site 1. You have verified that
both DNs are in the Phones partition. What is the cause of the issue?



  • A. The location configuration is resulting in insufficient bandwidth for this call.
  • B. The manager's CSS does not include Phones partition.
  • C. The manager's CSS does not include Employee partition.
  • D. The region configuration is resulting in codec negotiation issue.


Answer : B

Question 15

You recently added a Cisco Unity voice mail server to your Cisco CallManager IP
telephony solution. Your users are receiving voice mails, but the MWI light does not go off
after they have listened to all of their new voice mail messages. What must be verified and
possibly modified to resolve this issue?

  • A. Use the Port Usage tool to verify that the ports dedicated to MWI on/off are not over- utilized. Add another dedicated port if the current port is over-utilized.
  • B. Verify that the MWI "off directory number" has been configured on both the Cisco Unity server and the Cisco CallManager cluster. If it has not been configured, configure it on both the Cisco Unity server and Cisco CallManager cluster.
  • C. Verify the number of ports licensed for the Cisco Unity server is equal to the number of configured ports.
  • D. Verify that the calls are being sent to the correct ports on the Cisco Unity server. If the configured ports are incorrect on the CallManager cluster, change the values on the cluster to be correct.


Answer : B

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