Lucent Technologies Definity 8434DX User Manual page 7

Volume control button
For adjusting the volume of the following:
The speakerphone or speaker when a call is in progress
using the 2-way speakerphone or 1-way speaker
The handset receiver level while a call is in progress
using the handset
The tone ringer when the speaker is off and either the
handset is inactive or the tone ringer is active
Note: When the speaker is active, the ringer volume is
automatically reduced to a low setting. The volume is
restored when the speaker is turned off.
Remember: The Volume control button on your voice
terminal does not control the volume level of adjunct
equipment.
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