Ensure that you are using a 300-001 companion board and that the potentiometer is in a favorable position. This is not a volume control. Start by turning it all the way counter-clockwise until it stops and make small turns clockwise until there is a good sound on both ends. This adjustment can definitely affect the 2 way communication. The type of phone can also have an affect, ensure you test with a butt-set or test phone before determining the sound is bad, sometimes this can be a direct cause of the phones being used in the home. If this troubleshooting does not solve the issue please contact Channel Vision directly.