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IP phone display is blank and does not power on

Core Issue

These sources can power the Cisco IP Phone:

  • For connecting to a standard wall receptacle, the external power source has an optional Cisco AC adapter and power cord.      
  • The WS-X6348-RJ45V 10/100 switching module has an inline power provider to the Cisco IP Phone when connected to a Catalyst 3500, 4000 or 6000 family 10/100BaseTX switching module.
  • This module sends power on pins 1 and 2, and 3 and 6, which are also used to transmit Ethernet signals. Before the switch sends power, it tests for a Cisco IP Phone presence, avoiding damage to other Ethernet devices.   
  • The WS-PWR-PANEL power patch panel allows the Cisco IP Phone to be connected to existing Catalyst 4000, 5000 and 6000 family 10/100BaseTX switching modules.     

    This module sends power on pins 4, 5, 7 and 8, which are not used for Ethernet signaling. Like the inline power, the power patch panel also attempts to verify that the attached device is a Cisco IP Phone before providing power.

For more information, refer to the Providing Power to the Cisco IP Phone from Multiple Sources section of An Overview of the Cisco IP Phone.


To resolve Cisco IP Phone power problems, ascertain the phone's power source and check the respective source.

If the phone is powered using the WS-X6348-RJ45V 10/100 switching module, refer to the Troubleshoot In-Line Power Issues section of Understanding IP Phone In-Line Power Provisioning on the Catalyst 6500/6000 Switch.

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‎06-22-2009 05:37 PM
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