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Chapter 2 Preparing to Install the Cisco IP Phone on Your Network
Guidelines for Configuring Ports on the Cisco IP Phone models 7902G/7905G/7912G
2-10
Cisco IP Phone Administration Guide for Cisco CallManager 3.3, Cisco IP Phones 7902G/7905G/7912G
OL-6313-01
Related Topics
• Connecting the Cisco IP Phone to the Network, page 3-4
• Connecting to the Network, page 2-8
• Understanding Interactions with Other Cisco IP Telephony Products,
page 2-1
• Power Source Design, page 2-10
• Redundancy Feature, page 2-11
Power Source Design
The phone and switch automatically determine which power source the phone
uses. If the power has to be switched to a different source, the phone user will
experience different results based on which power source is being used by the
phone.
Use the following information to choose a power source for the phone:
• If you plug a phone into the optional power supply before plugging it into the
network, the phone is powered by the power supply.
• If you then unplug the phone from the power supply, the phone resets. If the
switch port is configured for 10/100 Mbps, the switch recognizes the loss of
power and brings the phone back up.
• If the switch port is configured for 10 Mbps only, then you must unplug the
network connection and plug it back into the phone for the switch to
recognize the phone’s loss of power.
• If, however, you plugged the network connection into the phone before you
plugged in the power cord, the phone receives power through the switch, and
unplugging the power cord will not bring down the phone. If the switch
reboots, the phone will then be powered by the power cord.
Related Topics
• Connecting the Cisco IP Phone to the Network, page 3-4
• Connecting to the Network, page 2-8
• Understanding Interactions with Other Cisco IP Telephony Products,
page 2-1
• Providing Power to the Cisco IP Phone, page 2-9