Cisco 8831NR Administration Manual page 141

Troubleshooting and Maintenance
Summary
Poor voice quality when calling
digital cell conference phones using
the G.729 codec (protocol)
Caution
Prolonged broadcast storms cause
conference phones to reset, or be
unable to make or answer a call
Sound sample mismatch between
the conference phone and another
device
Troubleshooting Procedures
These procedures can be used to identify and correct problems.
Check TFTP Settings
Procedure
Step 1
You can determine the IP address of the TFTP server used by the conference phone by choosing Apps >
Admin Settings > Network Setup > IPv4 Configuration > TFTP Server 1 .
Step 2
If you have assigned a static IP address to the conference phone, you must manually enter a setting for the
TFTP Server 1 option.
Step 3
If you are using Dynamic Host Configuration Protocol (DHCP), the conference phone obtains the address for
the Trivial File Transfer Protocol (TFTP) server from the DHCP server. A valid TFTP server must be set in
DHCP option 150 or option 66 on the DHCP server.
Step 4
You can also enable the conference phone to use an alternate TFTP server. Such a setting is particularly useful
if the conference phone was recently moved from one location to another.
Explanation
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 a Cisco Unified IP Conference Phone and a digital
cellular conference phone will have poor voice quality. Use G.729 only
Using a cell, mobile, or
when absolutely necessary.
GSM conference phone,
or two-way radio in For more information, see the Cisco Unified Communications Manager
close proximity to a application online help.
Cisco Unified IP
Conference Phone 8831
might cause interference.
For more information,
see the manufacturer's
documentation of the
interfering device.
A prolonged Layer 2 broadcast storm (lasting several minutes) on the
voice VLAN may cause conference phones to reset, lose an active call,
or be unable to initiate or answer a call. conference phones may not
come up until a broadcast storm ends.
The RxSize and the TxSize statistics show the size of the voice packets
that are being used in a conversation between this conference phone
and the other device. The values of these statistics should match.
See
these statistics.
Cisco Unified IP Conference Phone 8831 and 8831NR Administration Guide
Call Statistics Screen, on page 108
Troubleshooting Procedures
for information about displaying
131