Samsung HM3100 Manual page 42

Press the Multi-Function button twice to redial the last number of the other phone,
see page 36.
Depending on the phone, pressing the Multi-Function button will display call history
instead of redialling.
Dialling a number by voice
Press the Multi-Function button and say a name. You can dial a number of the first
phone.
Available call functions may vary by the phone.
Answering a call
Press the Multi-Function button to answer a call when you hear incoming call tones.
When two calls from the two connected phones come in, you can answer the call
of the first phone.
Ending a call
Press the Multi-Function button to end a call.
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