If the far side is hearing an echo or distortion, the microphone connected to your Lifesize system may be too close to the speakers. Repositioning the microphone may solve this problem.
Poor audio reception from the far end may be caused by highly reverberant rooms. If you are experiencing poor audio reception, add more sound absorbency to the room and speak in close proximity to the phone or microphone.
Degradation in the audio quality can also be caused by faulty microphones.
If dust and debris are on the microphones clean the top surface of the units with a soft, slightly damp cloth. Do not use any kind of liquid or aerosol cleaner on Lifesize devices that include microphones.