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Cisco Unified IP Phone 7970G/7971G-GE Administration Guide for Cisco Unified Communications Manager 6.1
OL-14626-01
Chapter 9 Troubleshooting and Maintenance
General Troubleshooting Tips
General Troubleshooting Tips
Table 9-2
provides general troubleshooting information for the Cisco Unified IP
Phone.
Table 9-2
Cisco Unified IP Phone Troubleshooting
Summary
Explanation
Daisy-chaining IP
phones
Cisco does not support connecting an IP phone to
another IP phone through the PC port. Each IP phone
should directly connect to a switch port. If phones
are connected together in a line (by using the PC
port), the phones will not work.
Poor quality when
calling digital cell
phones using the G.729
protocol
In Cisco Unified Communications Manager, you can
configure the network to use the G.729 protocol (the
default is G.711). When using G.729, calls between
an IP phone and a digital cellular phone will have
poor voice quality. Use G.729 only when absolutely
necessary.
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.
Summary of Contents for 7970G - IP Phone VoIP
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