LG G3100 User Manual page 195

During a call, the following menus will be displayed, not in a standby
mode.
You can place a call on hold or retrieve by just pressing the [Send]
key. When a call is made or answered, press the [Send] key to place
it on hold. When a call is held, press the [Send] key to make it active.
You can get a dial number from phonebook to make a second call.
Press [Names] key then select . To save the dial number into
phonebook during call, press [Names] key then select .
To switch between two calls, select the [Options] key, then select
Swap or just press [Send] key.
You can make one of two calls focused by pressing up/down arrow
key. If you want to end one of two calls, make the call you want to
end focused, then press [End] key when the call you want to end is
focused.
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