Information Technology Reference
In-Depth Information
server as well as a specific configuration file for the phone (the configuration file
should have the MAC address of the IP phone in the filename), and verify that you
entered the create cnf-files command from telephony-service configuration mode to
generate the necessary configuration files on the TFTP server.
Check the IP phone:
If you have physical access to the IP phone, navigate to the
network settings page (using the Settings button on the phone). Verify that the IP
phone is configured (either statically or via DHCP) for the appropriate TFTP server IP
address.
■
Issue 5: CME Server
The final troubleshooting step is to investigate the CME server itself. The most common
CME issue encountered is a “Registration Rejected” error message on the IP phone. See-
ing this error is actually fantastic news: It means that the IP phone is moving through the
entire boot process but fails when trying to register with the CME router. Almost 100% of
your focus should be on the ephone settings. A registration rejected message almost al-
ways appears because the IP phone has not been properly configured in CME. First, vali-
date that an ephone entry exists in your CME configuration for the IP phone in question.
If so, verify that the MAC address entered for the ephone matches the MAC address of
the IP phone. Don't trust the sticker on the outside of the IP phone! Verify the MAC ad-
dress directly from the phone settings or the Cisco switch (viewing the dynamic MAC ad-
dresses learned on the port connecting to the IP phone).
If the MAC address appears correct in the CME configuration, try enabling auto-registra-
tion in CME (type auto-reg-ephone under the telephony-service configuration). This
should allow the phone to register without any extension assignment. You can then vali-
date the MAC address of the IP phone by entering the show ephone command. If you
want to get into the nitty-gritty, issue a debug ephone detail command, and you'll be able
to watch the IP phone registration process line by line. Be careful with this command, be-
cause it might become overwhelming (to both you and your CME router) if you have
many phones registering at the same time.
Troubleshooting Dial-Plan and QoS Issues
Although this topic is a bit outside the current scope of the CCNA Voice exam, it is ex-
tremely advantageous to you if you are able to troubleshoot basic dial-plan and QoS is-
sues. These issues occur after the IP phone successfully registers with the CME router and
attempts to place calls. Symptoms that arise range from call failure when dialing (fast
busy/reorder tone) to static, distortion, or dropped calls after the call is connected. The
former issue is typically related to a misconfigured dial-plan, while the latter issue is typi-
cally related to QoS.
Dial-Plan Issues
To troubleshoot issues related to the dial-plan on the CME router, you must first focus on
the dial peers. Remember, the dial-peer configuration builds the routing table for your
voice calls. If you configured it inaccurately or incompletely, calls will not complete. Al-
though you can use many commands to troubleshoot calls, two key commands rise to the
surface: show dial-peer voice summary and debug voip dialpeer.
