General Troubleshooting Information
The following table provides general troubleshooting information for the Cisco IP Phone.
Summary |
Explanation |
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Connecting a Cisco IP Phone to another Cisco IP Phone |
Cisco does not support connecting an IP phone to another IP Phone through the PC port. Each IP Phone should connect directly to a switch port. If phones are connected together in a line by using the PC port, the phones do not work. |
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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. |
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Moving a network connection from the phone to a workstation |
If you power your phone through the network connection, you must be careful if you decide to unplug the network connection of the phone and plug the cable into a desktop computer.
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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 Apply a Phone Password for details.
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Codec mismatch between the phone and another device |
The RxType and the TxType statistics show the codec that is used for a conversation between this Cisco 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. |
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Sound sample mismatch between the phone and another device |
The RxSize and the TxSize statistics show the size of the voice packets that are used in a conversation between this Cisco IP Phone and the other device. The values of these statistics should match. |
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Loopback condition |
A loopback condition can occur when the following conditions are met:
In this case, the switch port on the phone can become disabled and the following message appears in the switch console log: HALF_DUX_COLLISION_EXCEED_THRESHOLD To resolve this problem, reenable the port from the switch. |