IP addressing – Configuration of the IP phones is one of the basic setup requirement and it needs to be checked to ensure it should be correct by using settings button on the phone.  Before responding to an IP phone,  it is crucial for Cisco Unified CME to know what source the IP address it is responding to.  This is done using ip source-address command in the telephony service configuration mode.

The most common problem in CME deployment is the registration of the IP phones.  This why it is important to understand the boot process is critical in Cisco IP phones.  Once a Cisco IP phone receives VLAN information from switch, it begins sending DHCP requests, during this state the onscreen display will be words “Configuring IP”.  If the phone seems to stay there for extended period of time and then reboots, there could be an issue with the DHCP service.

So you need to check if the IP phone is receiving an IP address from the phone itself and you can check this by pressing the Settings button, selecting the Network Configuration option and scrolling down to the IP Address section.  This will let you verify the IP address of phone.  If the phone consistently doesn’t display the IP address, the problem is most likely related to a voice VLAN or DHCP configuration.   You will need to verify the VLAN settings on the interface, DHCP pool configuration,  and ensure proper configuration with the ip-address helper command.

Debugging of TFTP Server – use the debug tftp events to check the Cisco Unified Communication Manager Express router is correctly providing the firmware and XML files.  The correct firmware file should be loaded in memory.  We also need to tell telephony service which firmware files it should use for various models of Cisco IP phones it is supporting. This is done using load command as shown below.

CME_voice (Config-telephony) # load?


12SP      select the firmware load file for 12SP+ and 30VIP phones

7902       select the firmware load file for 7902

7905       select the firmware load file for 7905

7910       select the firmware load file for 7910

7912       select the firmware load file for 7912

7914       select the firmware load file for 7914

7920       select the firmware load file for 7920

7935       select the firmware load file for 7935 conference station

7936       select the firmware load file for 7936

7960-7940 select the firmware load file for telecaster 7960 and 7940 phones

7970       select the firmware load file for 7970

7971       select the firmware load file for 7971

ATA        select the firmware load file for ATA

CME_voice (Config-telephony) #  load 7960?

WORD firmware filename for telecaster 7960 and 7940

[without .bin]

CME_voice (Config-telephony) # load 7960 P00308000500

Updating cnf files

CNF files updating complete


We also need to confirm the files served up by the TFTP service on CME by using the show telephony-service tftp-bindings command.

Once we are sure that the IP address assignment working properly, we can  move to next step of the boot process; the TFTP server.  After the phone passes  the “configuring IP” message,  it will change to “configuring CM List”.  During this time the IP phone will attempt to download configuration file from TFTP server.  If the phone stays on this message for extended time there could be a communication issue with TFTP server.  So the first step is to ping TFTP server to ensure path of communication is intact between both.  Next we will verify that the TFTP server is up and serving up the right files.  In case we are using the CME router as TFTP server,  we can use debug tftp events command.

CME_voice# debug tftp events

The output of above command will show either an IP phone sending a TFTP request for a file or a CME router sending a file via TFTP to the IP phone.  If you see a TFTP: looking request in the debug output which is not followed by opened or TFTP: finished message, the TFTP server might be not making the correct files available.  We can use the show telephony-service tftp-bindings command to verify files provided by TFTP.

Files in Flash Memory – The correct firmware files should be in flash memory of the Cisco Unified Communication Manager Express router.  We can use the show flash command to display contents of flash memory on the device.

Firmware Installations on Phones – We can use the debug ephone registar command to confirm the firmware version being installed on our phones.

Locale Settings – We can use the show telephony-service tftp-bindings command to view the files which the TFTP server is providing.  CME has ability to support non English local settings for IP phones which comes in two flavors; network and user locale.  We need to ensure correct locale settings are configured on the IP phones for them to function correctly.

Phone Setup – We can use the show ephone command to view status of the ephone and ensure they are registered correctly.  To ensure that Cisco Unified CME router can begin registering and supporting the IP phones, it needs to know the number of phones and directory numbers it will be supporting.  If you see a phone status shown as DECEASED in show ephone command output, that means the CME router has lost connectivity with IP phone through the TCP keepalive failure.  The UNGREGISTERED status indicates the CME router has closed the connection to IP phone in normal manner.

By default both values are set to zero, so the router doesn’t support any VOIP devices. To configure this value we use the following command syntax:

CME_voice (config) # telephony-service

CME_voice (config-telephony) # max-ephones?

maximum phones to support

CME_voice (config-telephony) # max-ephones 24

CME_voice (config-telephony) # max-dn?

maximum directory numbers to support

CME_voice (config-telephony) # max-dn 48

The max-ephone parameter is used to configure maximum number of IP phones the router will be supporting. Whereas the max-dn command will specify maximum number of directory numbers supported.  The max-ephones parameters impact the router memory directly.  The max-telephone parameter should not be higher than number of licenses purchased for the CME system.

Configuration Review – The show running-config command displays and verifies ephone-dn configuration.  Once the IP phone downloads all the necessary files, it will contact the CME router to receive line assignments and feature support.  All communication between the IP phone and CME router occurs over skinny client control protocol (SCCP).  We can use the debug ephone registar command to verify ephone registration process.  SCCP sends the initial request and the CME router searches and finds the configuration file for the IP phone.  To verify failed ephone registrations we can use show ephone attempted-registrations command.

This concludes the CCNA Voice exam topic on troubleshooting methods for Cisco Unified Communication Manager Express.