Samsung SBH500 Instruction Manual page 18

Using options during a call
You can use the following functions to control your call while a
call is in progress.
Adjusting the volume
Press [+] or [-] to adjust the earpiece volume while talking.
At very high volumes, prolonged listening to the
headset can damage your hearing.
Muting the microphone
Press and hold [+] or [-] to turn off the microphone so that
the person with whom you are speaking cannot hear you.
Press and hold [+] or [-] again to turn back on the
microphone.
Placing a call on hold
Press and hold [ ] to place the current call on hold.
Answering a second call
Press and hold [ ] to answer a second call when you hear a
call waiting tone. The first call places on hold.
To reject a second call, press [ ].
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