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Cisco Unified IP Phone 6921, 6941, 6945, and 6961 Administration Guide for Cisco Unified Communications Manager 8.5 (SCCP and SIP)
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Chapter
Troubleshooting Cisco Unified IP Phone Security
Step 4 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.
Step 5 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 “Determining the MAC Address for a Cisco Unified IP Phone” section on
page 2-13.
Step 6 Power cycle the phone.

Checking Power Connection

In most cases, a phone will restart 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 gets connected to
an external power supply.
Troubleshooting Cisco Unified IP Phone Security
Table 9-1 provides troubleshooting information for the security features on the Cisco Unified IP Phone.
For information relating to the solutions for any of these issues, and for additional troubleshooting
information about security and encryption, refer to Cisco Unified Communications Manager Security
Guide.
Table 9-1 Cisco Unified IP Phone Security Troubleshooting
Problem Possible Cause
Device authentication error. CTL file does not have a Cisco Unified Communications Manager certificate
or has an incorrect certificate.
Phone cannot authenticate CTL file. The security token that signed the updated CTL file does not exist in the CTL
file on the phone.
Phone cannot authenticate any of the
configuration files other than the CTL file. Bad TFTP record.
Phone does not register with Cisco Unified
Communications Manager. The CTL file does not contain the correct information for the Cisco
Unified Communications Manager server.
Phone does not request signed configuration
files. The CTL file does not contain any TFTP entries with certificates.