Troubleshooting; General Troubleshooting Information - Cisco 7821 Administration Manual

Troubleshooting

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General Troubleshooting Information

The following table provides general troubleshooting information for the Cisco IP Phone.
Table 26: Cisco IP Phone Troubleshooting
Summary
Connecting a Cisco IP Phone to
another Cisco IP Phone
Prolonged broadcast storms cause IP
phones to reset, or be unable to make
or answer a call
General Troubleshooting Information, page 175
Startup Problems, page 177
Cisco IP Phone Reset Problems, page 180
Phone Cannot Connect to LAN, page 183
Cisco IP Phone Security Problems, page 183
Audio Problems, page 187
General Telephone Call Problems, page 188
Troubleshooting Procedures, page 189
Additional Troubleshooting Information, page 193
Control Debug Information from Cisco Unified Communications Manager, page 193
Cisco IP Phone 7821, 7841, and 7861 Administration Guide for Cisco Unified Communications Manager 10.0 (SIP)
C H A P T E R
Explanation
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.
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.
13
175