Troubleshooting guide

Hardware
79
Echo occurring
between IP
Phones
Layer 2 switch setting
problem.
1. Check the L2 switch for duplex mismatch and spanning tree.
2. Turn off spanning tree between the L2 switch and the IP Phone if
possible (use the PortFast setting).
3. In the Layer 2 Switch form of the System Administration Tool,
configure all L2 ports in the voice path with the same settings.
The recommended settings for the “Duplex Mode” field and the
“Flow Control” field is “Auto”.
4. If the network requires fixed settings, use the following:
- State - Enabled
- Speed - 100 Mb
- Duplex Mode - Full DX
- Flow Control - Enabled
- Voice VLAN - Tagged
5. If you change these fields to fixed settings, you must also set the
IP phones to use the fixed settings. You change the IP phone
settings through the Configuration menu. See page 188.
6. In the Configuration menu, select Hardware Config? and then
select Modify Port Setting and modify the settings.
Far end phone is on
handsfree
Check if far end is using handsfree. Switch to handset mode to see
if this corrects it, or lower the volume in handsfree mode. For best
results when using handsfree mode:
• ensure that the microphone (on the front edge of the telephone)
is unobstructed and not close to a reflecting surface, such as a
shelf.
• minimize background noise (such as printers, fans, and radios)
• sit within reach of the telephone
• speak at a normal volume towards the microphone.
In conference call, echo
is noticed from external
trunk
1. Identify the path between the two end points, and verify if Trunk
is always involved.
2. Check with Telco to see if the trunk is within specs. On a typical
T1, the input signal should be -15 dB. If it is too high(-5 dB for
example), echo may result. Keep a log to isolate the problem.
There is an audio path
between the users as
well as between the
phones.
Provide better acoustic shielding between users, e.g. close the
door, provide sound-deadening partitions.
Voice quality
issues appear
after a network
upgrade
Cisco IOS is upgraded
to IOS 12.2(37), Mitel
IP phones receive
DiffServ (DSCP) value
of 0 from LLDP resulting
in Voice Quality of
Service degradation.
Refer to Mitel Knowledge Base article 08-5191-00104.
Audio issues on
SIP, including
Music on Hold
Need to have
ENABLE_TX_CHAN_C
ONN feature enabled.
Refer to Mitel Knowledge Base article 11-5160-00010.
Note: This feature is available only on MCD 4.x and above.
Table 20: Audio Quality Troubleshooting(continued)
Symptom Prossible Cause Corrective Action
Page 4 of 4