CapTel 840: Adjusting Volume/Tone
You can increase the volume of the person’s voice coming through the handset, up to a 40dB gain from min/max on every call. Watch the lights above the VOLUME bar to see what level the volume is set to.
To increase the volume (make sounds louder) during a call, press the right side of the VOLUME bar.
To decrease the volume (make sounds softer) during a call, press the left side of the VOLUME bar.