Mute Button; Hold Function; Ethernet Switch - Plantronics IP40 Administration Manual

Once adjusted, the volume setting persists across calls, unless the headset is
disconnected when the IP40 headset adapter is not in a call or the IP40 headset
adapter is rebooted. When the headset is disconnected in the idle state, the receive
volume level reverts to the default setting.
The transmit volume is calibrated at the factory and does not require adjustment.

2.3 Mute Button

During a call, pressing the mute button mutes the headset microphone on the headset
adapter. The mute button will turn red to indicate this and a mute tone is played. To
turn off the mute feature, press the button again. The mute status does not persist
across calls.
QD Connector
Figure 2 IP40 Underside View Showing Cable Routing and QD Location

2.4 Hold Function

During a call, if the headset is unplugged at the QD connector, the IP40 headset
adapter will attempt to place the other party on hold. If this was successful, the
Answer/End button will be yellow. Reconnecting the headset at the QD connector will
take the other party off hold and resume a normal call.

2.5 Ethernet Switch

The IP40 has two Ethernet ports that are switched / bridged with the internal Ethernet
5/29/2009 Plantronics IP40 Administration Guide Page 9