This chapter provides information that can assist you in troubleshooting problems with your Cisco Unified IP Phone or with your IP telephony network. It also explains how to maintain your voice network and clean your phone.
After installing a Cisco Unified IP Phone into your network and adding it to Cisco Unified Communications Manager, the phone should start up as described in the Phone Startup Verification. If the phone does not start up properly, see the following sections for troubleshooting information.
Cisco Unified IP Phone Does Not Go Through Normal Startup Process
When you connect a Cisco Unified IP Phone into the network port, the phone should go through its normal startup process as described in Phone Startup Verification.
If the phone does not go through the startup process, the cause may be faulty cables, bad connections, network outages, lack of power, and so on. Or, the phone may not be functional.
To determine whether the phone is functional, follow these suggestions to systematically eliminate these other potential problems:
Verify that the network port is functional:
Exchange the Ethernet cables with cables that you know are functional.
Disconnect a functioning Cisco Unified IP Phone from another port and connect it to this network port to verify the port is active.
Connect the Cisco Unified IP Phone that will not start up to a different network port that is known to be good.
Connect the Cisco Unified IP Phone that will not start up directly to the port on the switch, eliminating the patch panel connection in the office.
Verify that the phone is receiving power:
If you are using external power, verify that the electrical outlet is functional.
If you are using in-line power, use the external power supply instead.
If you are using the external power supply, switch with a unit that you know to be functional.
If the phone still does not start up properly, perform a factory reset of the phone. For instructions, see the Perform Factory Reset.
If after attempting these solutions, the phone still does not function, contact a Cisco technical support representative for additional assistance.
Cisco Unified IP Phone Does Not Register with Cisco Unified Communications Manager
If the phone proceeds past the first stage of the startup process (all LED buttons on) but the phone is not starting up properly. The phone cannot successfully start up unless it is connected to the Ethernet network and it has registered with a Cisco Unified Communications Manager server.
Phone status message display errors during startup.
While the phone cycles through the startup process, you can access status messages that might provide you with information about the cause of a problem. See the Device Logs for instructions about accessing status messages.
Phone Cannot Connect to TFTP Server or to Cisco Unified Communications Manager
If the network is down between the phone and either the TFTP server or Cisco Unified Communications Manager, the phone cannot start up properly.
The IP addressing and routing fields may not be correctly configured.
You should verify the IP addressing and routing settings on the phone. If you are using DHCP, the DHCP server should provide these values. If you have assigned a static IP address to the phone, you must enter these values manually. See DHCP Setting Verification.
Cisco CallManager and TFTP Services Are Not Running
If the Cisco CallManager or TFTP services are not running, phones may not be able to start up properly. In such a situation, it is likely that you are experiencing a systemwide failure, and other phones and devices are unable to start up properly.
If the Cisco CallManager service is not running, all devices on the network that rely on it to make phone calls are affected. If the TFTP service is not running, many devices cannot start up successfully. For more information, see Start Service.
Configuration File Corruption
If you continue to have problems with a particular phone that other suggestions in this chapter do not resolve, the configuration file may be corrupted.
The phone is not registered with the Cisco Unified Communications Manager.
A Cisco Unified IP Phone can register with a Cisco Unified Communications Manager server only if the phone has been added to the server or if auto-registration is enabled and if there is a sufficient number of unit licenses. Review the information and procedures in the Cisco Unified Communications Manager Phone Addition Methods to ensure that the phone has been added to the Cisco Unified Communications Manager database.
To verify that the phone is in the Cisco Unified Communications Manager database, choose Device > Phone > Find from Cisco Unified Communications Manager Administration to search for the phone based on its MAC Address. For information about determining a MAC address, see the MAC Address for Cisco Unified IP Phone Determination.
If the phone is already in the Cisco Unified Communications Manager database, its configuration file may be damaged. See the Create New Configuration File for assistance.
For more information on licensing, see the "Licenses for Phones" section in the Cisco Unified Communications Manager System Guide.
Cisco Unified IP Phone Cannot Obtain IP Address
If a phone cannot obtain an IP address when it starts up, the phone may not be on the same network or VLAN as the DHCP server, or the switch port to which the phone connects may be disabled.
Ensure that the network or VLAN to which the phone connects has access to the DHCP server, and ensure that the switch port is enabled.
Cisco Unified IP Phone Resets Unexpectedly
If users report that their phones are resetting during calls or while idle on their desk, you should investigate the cause. If the network connection and Cisco Unified Communications Manager connection are stable, a Cisco Unified IP Phone should not reset on its own.
Typically, a phone resets if it has problems connecting to the Ethernet network or to Cisco Unified Communications Manager.
Verify that the Ethernet connection to which the Cisco Unified IP Phone connects is up. For example, check whether the particular port or switch to which the phone connects is down and that the switch is not rebooting. Also ensure that no cable breaks exist.
Intermittent network outages
Your network may be experiencing intermittent outages.
Intermittent network outages affect data and voice traffic differently. Your network might be experiencing intermittent outages without detection. If so, data traffic can resend lost packets and verify that packets are received and transmitted. However, voice traffic cannot recapture lost packets. Rather than retransmitting a lost network connection, the phone resets and attempts to reconnect to the network. Contact the system administrator for information on known problems in the voice network.
DHCP Settings Errors
The DHCP settings may be incorrect.
Verify that you have properly configured the phone to use DHCP. See Configuration Menus for more information. Verify that the DHCP server is set up properly. Verify the DHCP lease duration. Cisco recommends that you set it to 8 days.
Static IP Address Settings Errors
The static IP address assigned to the phone may be incorrect.
If the phone is assigned a static IP address, verify that you have entered the correct settings. See Configuration Menus for more information.
Voice VLAN Setup Errors
If the Cisco Unified IP Phone appears to reset during heavy network usage (for example, following extensive web surfing on a computer connected to the same switch as the phone), it is likely that you do not have a voice VLAN configured.
If you are not the only administrator with access to Cisco Unified Communications Manager, you should verify that no one else has intentionally reset the phones.
You can check whether a Cisco Unified IP Phone received a command from Cisco Unified Communications Manager to reset by pressing Applications on the phone and choosing Admin Settings > Status > Network Statistics. If the phone was recently reset, one of these messages appears:
If the Restart Cause field displays Reset-Reset, the phone closed due to receiving a Reset/Reset from Cisco Unified Communications Manager Administration.
If the Restart Cause field displays Reset-Restart, the phone closed due to receiving a Reset/Restart from Cisco Unified Communications Manager Administration.
DNS or Other Connectivity Errors
The phone reset continues and you suspect DNS or other connectivity issues.
In most cases, a phone restarts if it powers up by using external power but loses that connection and switches to PoE. Similarly, a phone may restart if it powers up by using PoE and then connects to an external power supply.
The following sections describe how to resolve audio problems.
One or more people on a call do not hear any audio.
When at least one person in a call does not receive audio, IP connectivity between phones is not established. Check the configuration of routers and switches to ensure that IP connectivity is properly configured.
A user complains of choppy speech on a call.
There may be a mismatch in the jitter configuration.
Check the AvgJtr and the MaxJtr statistics. A large variance between these statistics might indicate a problem with jitter on the network or periodic high rates of network activity.
Poor Audio Quality with Calls That Route Outside Cisco Unified Communications Manager
Poor quality occurs with tandem audio encoding. Tandem encoding can occur when calls are made between an IP Phone and a digital cellular phone, when a conference bridge is used, or in situations where IP-to-IP calls are partially routed across the PSTN.
In these cases, use of voice codecs such as G.729 and iLBC may result in poor voice quality.
Use the G.729 and iLBC codecs only when absolutely necessary.
General Telephone Call Problems
The following sections help troubleshoot general telephone call problem.
A user complains about not being able to make a call.
The phone does not have a DHCP IP address, is unable to register to Cisco Unified Communications Manager. Phones with an LCD display show the message Configuring IP or Registering. Phones without an LCD display play the reorder tone (instead of dial tone) in the handset when the user attempts to make a call.
Verify the following:
The Ethernet cable is attached.
The Cisco CallManager service is running on the Cisco Unified Communications Manager server.
Both phones are registered to the same Cisco Unified Communications Manager.
Audio server debug and capture logs are enabled for both phones. If needed, enable Java debug.
Phone Does Not Recognize DTMF Digits or Digits Are Delayed
The user complains that numbers are missed or delayed when the keypad is used.
Pressing the keys too quickly can result in missed or delayed digits.
Keys should not be pressed rapidly.
These procedures can be used to identify and correct problems.
You can determine the IP address of the TFTP server used by the phone by pressing Applications, then selecting Admin Settings > Network Setup > IPv4 > TFTP Server 1.
If you have assigned a static IP address to the phone, you must manually enter a setting for the TFTP Server 1 option. See the Configuration Menus.
If you are using DHCP, the phone obtains the address for the TFTP server from the DHCP server. Check the IP address configured in Option 150 or Option 66.
You can also enable the phone to use an alternate TFTP server. Such a setting is particularly useful if the phone was recently moved from one location to another. See the Configuration Menus for instructions.
DHCP Setting Verification
On the Cisco Unified IP Phone, press Applications, then select Admin Settings > Network Setup > IPv4 and then look at the following options:
IP Address, Subnet Mask, Default Router: If you have assigned a static IP address to the phone, you must manually enter settings for these options. See the Configuration Menus for instructions.
A service must be activated before it can be started or stopped. To activate a service, choose Tools > Service Activation.
To start a service, follow these steps:
From Cisco Unified Communications Manager Administration, choose Cisco Unified Serviceability from the Navigation drop-down list and click Go.
Choose Tools > Control Center - Feature Services.
Choose the primary Cisco Unified Communications Manager server from the Server drop-down list.
The window displays the service names for the server that you chose, the status of the services, and a service control panel to start or stop a service.
If a service has stopped, click the corresponding radio button and then click Start.
The Service Status symbol changes from a square to an arrow.
Create New Configuration File
If you continue to have problems with a particular phone that other suggestions in this chapter do not resolve, the configuration file may be corrupted.
When you remove a phone from the Cisco Unified Communications Manager database, its configuration file is deleted from the Cisco Unified Communications Manager TFTP server. The phone’s directory number or numbers remain in the Cisco Unified Communications Manager database. They are called unassigned DNs and can be used for other devices. If unassigned DNs are not used by other devices, delete them from the Cisco Unified Communications Manager database. You can use the Route Plan Report to view and delete unassigned reference numbers. See Cisco Unified Communications Manager Administration Guide for more information.
Changing the buttons on a phone button template, or assigning a different phone button template to a phone, may result in directory numbers that are no longer accessible from the phone. The directory numbers are still assigned to the phone in the Cisco Unified Communications Manager database, but there is no button on the phone with which calls can be answered. These directory numbers should be removed from the phone and deleted if necessary.
To create a new configuration file, perform these steps:
From Cisco Unified Communications Manager, choose Device > Phone > Find to locate the phone experiencing problems.
Choose Delete to remove the phone from the Cisco Unified Communications Manager database.
Assign static IP values to the phone. See the Configuration Menus for instructions. Use the same default router setting used for other functioning Cisco Unified IP Phones.
Assign a TFTP server. See the Configuration Menus for instructions. Use the same TFTP server used for other functioning Cisco Unified IP Phones.
On the Cisco Unified Communications Manager server, verify that the local host files have the correct Cisco Unified Communications Manager server name mapped to the correct IP address.
From Cisco Unified Communications Manager, choose System > Server and verify that the server is referred to by its IP address and not by its DNS name.
From Cisco Unified Communications Manager, choose Device > Phone > Find and verify that you have assigned the correct MAC address to this Cisco Unified IP Phone. For information about determining a MAC address, see the MAC Address for Cisco Unified IP Phone Determination.
Power cycle the phone.
General Troubleshooting Information
The following table provides general troubleshooting information for the Cisco Unified IP Phone.
Table 1 Cisco Unified IP Phone Troubleshooting
Connecting a Cisco Unified IP Phone to another Cisco Unified IP Phone.
Cisco does not support connecting an IP phone to another IP phone through the PC port. Each IP phone should directly connect to a switch port. If phones are connected together in a line (by using the PC port), the phones will not work.
Prolonged broadcast storms cause IP phones to reset, or be unable to make or answer a call.
A prolonged Layer 2 broadcast storm (lasting several minutes) on the voice VLAN may cause IP phones to reset, lose an active call, or be unable to initiate or answer a call. Phones may not come up until a broadcast storm ends.
Moving a network connection from the phone to a workstation.
If you are powering your phone through the network connection, you must be careful if you decide to unplug the phone’s network connection and plug the cable into a desktop computer.
The computer’s network card cannot receive power through the network connection; if power comes through the connection, the network card can be destroyed. To protect a network card, wait 10 seconds or longer after unplugging the cable from the phone before plugging it into a computer. This delay gives the switch enough time to recognize that there is no longer a phone on the line and to stop providing power to the cable.
Changing the telephone configuration.
By default, the network configuration options are locked to prevent users from making changes that could impact their network connectivity. You must unlock the network configuration options before you can configure them. See the Configuration Menus for details.
The phone resets when it loses contact with the Cisco Unified Communications Manager software. This lost connection can be due to any network connectivity disruption, including cable breaks, switch outages, and switch reboots.
Codec mismatch between the phone and another device.
The RxType and the TxType statistics show the codec that is being used for a conversation between this Cisco Unified IP phone and the other device. The values of these statistics should match. If they do not, verify that the other device can handle the codec conversation, or that a transcoder is in place to handle the service.
Sound sample mismatch between the phone and another device.
The RxSize and the TxSize statistics show the size of the voice packets that are being used in a conversation between this Cisco Unified IP phone and the other device. The values of these statistics should match.
A loopback condition can occur when the following conditions are met:
The SW Port Configuration option in the Network Configuration menu on the phone is set to 10 Half (10-BaseT / half duplex)
The phone receives power from an external power supply
The phone is powered down (the power supply is disconnected)
In this case, the switch port on the phone can become disabled and the following message will appear in the switch console log:
To resolve this problem, re-enable the port from the switch.
Additional Troubleshooting Information
If you have additional questions about troubleshooting the Cisco Unified IP Phones, several Cisco.com web sites can provide you with more tips. Choose from the sites available for your access level.
Performing a basic reset of a Cisco Unified IP Phone provides a way to recover if the phone experiences an error and provides a way to reset or restore various configuration and security settings.
The following table describes the ways to perform a basic reset. You can reset a phone with any of these operations after the phone has started up. Choose the operation that is appropriate for your situation.
Table 2 Basic Reset Methods
Unplug the power cable and plug it back in.
Resets any user and network configuration changes that you have made, but that the phone has not written to its Flash memory, to previously saved settings, then restarts the phone.
Reset the phone to its factory settings.
Resets user and network configuration settings to their default values, and restarts the phone.
Perform Factory Reset
When you perform a factory reset of the Cisco Unified IP Phone, the following information is erased or reset to its default value:
User configuration settings: Reset to default values
Network configuration settings: Reset to default values
Call histories: Erased
Locale information: Reset to default values
Phone application: Erased (phone recovers by using the image in the inactive partition of flash to boot up).
Before you perform a factory reset, ensure that the following conditions are met:
The phone must be on a DHCP-enabled network.
A valid TFTP server must be set in DHCP option 150 or option 66 on the DHCP server.
To perform a factory reset of a phone, you can press Applications and choose Admin Settings > Reset All or you can perform the following steps:
Unplug the power cable from the phone and then plug it back in.
The phone begins its power-up cycle.
While the phone is powering up, press and hold # until the Line LED turns green.
Release the # button and press 123456789*0#.
The phone reboots when it is finished.
Voice Quality Monitoring
To measure the voice quality of calls that are sent and received within the network, Cisco Unified IP Phones use these statistical metrics that are based on concealment events. The DSP plays concealment frames to mask frame loss in the voice packet stream.
Concealment Ratio metrics: Show the ratio of concealment frames over total speech frames. An interval conceal ratio is calculated every 3 seconds.
Concealed Second metrics: Show the number of seconds in which the DSP plays concealment frames due to lost frames. A severely concealed second is a second in which the DSP plays more than five percent concealment frames.
Mean Opinion Score (MOS) for Listening Quality (LQK) Voice Metrics: Uses a numeric score to estimate the relative voice-listening quality. The Cisco Unified IP Phones calculate the MOS LQK based audible-concealment events due to a frame loss in the preceding 8 seconds and includes weighting factors such as codec type and frame size. MOS LQK scores are produced by a Cisco-proprietary algorithm, the Cisco Voice Transmission Quality (CVTQ) index. Depending on the MOS LQK version number, these scores may comply with the International Telecommunications Union (ITU) standard P.564. (This standard defines evaluation methods and performance accuracy targets that predict listening quality scores based on observation of actual network impairment.)
Concealment ratio and concealment seconds are primary measurements based on frame loss. A Conceal Ratio of zero indicates that the IP network is delivering frames and packets on time with no loss.
You can access voice quality metrics remotely by using Streaming Statistics (see the Remote Monitoring chapter).
Voice Quality Metrics
When using the metrics for monitoring voice quality, note the typical scores under normal conditions of zero packet loss and use the metrics as a baseline for comparison.
It is also important to distinguish significant changes from random changes in metrics. Significant changes are scores that change about 0.2 MOS or more and persist in calls that last longer than 30 seconds. Conceal ratio changes indicate a frame loss greater than 3 percent.
The MOS LQK scores can vary based on the codec that the Cisco Unified IP Phone uses. The following codecs provide these corresponding maximum MOS LQK scores under normal conditions with zero frame loss for Cisco Unified SIP Phone 3905:
G.711: 4.5 MOS LQK
G729A/AB: 3.7 MOS LQK
Cisco Voice Transmission Quality (CVTQ) does not support wideband (7 kHz) speech codecs, because ITU has not defined the extension of the technique to wideband.
Reporting G.711-scale MOS scores for wideband calls through the use of CVTQ allows basic-quality classifications to be indicated as good/normal or bad/abnormal. Calls with high scores (approximately 4.5) indicate high quality or a low packet loss, and lower scores (approximately 3.5) indicate low quality or a high packet loss.
Unlike MOS, the conceal ratio and concealed seconds metrics remain valid and useful for both wideband and narrowband calls.
A conceal ratio of zero indicates that the IP network is delivering frames and packets on time with no loss.
When you observe significant and persistent changes to metrics, use the following table for general troubleshooting information.
Table 3 Changes to Voice Quality Metrics
Conceal Ratio and Conceal Seconds increase significantly
Network impairment from packet loss or high jitter.
Conceal Ratio is near or at zero, but the voice quality is poor.
Noise or distortion in the audio channel such as echo or audio levels.
Tandem calls that undergo multiple encode/decode such as calls to a cellular network or calling card network.
Acoustic problems coming from a speakerphone, handsfree cellular phone or wireless headset.
Check packet transmit (TxCnt) and packet receive (RxCnt) counters to verify that voice packets are flowing.
MOS LQK scores decrease significantly
Network impairment from packet loss or high jitter levels:
Average MOS LQK decreases may indicate widespread and uniform impairment.
Individual MOS LQK decreases may indicate bursty impairment.
Cross-check the conceal ratio and conceal seconds for evidence of packet loss and jitter.
MOS LQK scores increase significantly
Check to see if the phone is using a different codec than expected (RxType and TxType).
Check to see if the MOS LQK version changed after a firmware upgrade.
Voice quality metrics do not account for noise or distortion, only frame loss.
Cisco Unified IP Phone Cleaning
To clean your Cisco Unified IP phone, use only a dry soft cloth to gently wipe the phone. Do not apply liquids or powders directly on the phone. As with all non-weather-proof electronics, liquids and powders can damage the components and cause failures.