If the red light comes on a lot it indicates that the DM15 considers that the call has a lot of startle events. Following one startle event, the VistaPlus temporarily freezes the automatic volume adjustment as part of the process of ensuring maximum protection for subsequent events. This can result in the anti-startle function triggering during normal speech. Reduce the volume on the VistaPlus to reset the volume leveling function to solve this problem. The volume can then be turned back up on the VistaPlus if desired.