Yealink SIP-T2 SERIES Administrator's Manual page 939

jitter, due to message recombination of transmission or receiving equipment (e.g.,
timeout handling, retransmission mechanism, buffer under run).
Noisy equipment, such as a computer or a fan, may cause voice interference. Turn

off any noisy equipment.
Line issues can also cause this problem; disconnect the old line and redial the call

to ensure another line may provide better connection.
If the caller and receiver cannot hear anything - there is no sound at all when the other
party picks up the call, the possible reason could be: the phone cannot send the
real-time transport protocol (RTP) streams, in which audio data is transmitted, to the
connected call.
Try to disable the 180 ring workaround feature. For more information, refer to
Workaround on page 350.
Ensure that the 180 ring workaround feature is disabled. For more information, refer to
180 Ring Workaround on page 350.
Ensure that the display device has suitable resolution.

Check whether the packet has been lost. For more information on packet loss, refer

to Getting Information from Talk Statistics
Ensure that camera settings are configured correctly, such as brightness and white

balance.
Avoid high-intensity indoor light or direct sunlight on the camera.

Ensure that the IP phone is powered off.

Check if the camera is not properly connected to the phone.

Make sure that the shutter switch of the camera is opened.

on page 908.
Troubleshooting
180 Ring
917