NTT docomo STYLE Series Instruction Manual page 362

Auto answer setting
Receiving a call automatically when
an earphone is connected
Automatically answer voice/Videophone calls received while
the Stereo Earphone Set 01 (sold separately) is connected.
When the Stereo Earphone Set 01 is not connected, Auto answer
setting is not available even if set to [ON].
1
In the Custom menu, select [Settings]/[Phone
settings]/[Incoming settings]/[Auto answer
setting].
2
Select [ON]/enter a ring time/t.
Calls are answered without ringing or vibrating when the ring time
is set to [000 seconds].
Calls from other parties set for Reject calls are not answered.
Set different Auto answer and Record message ring times.
If both Voice Mail Service and Auto answer setting are enabled,
and the same number of seconds is set for both services, then
Voice Mail Service takes priority. To prioritize Auto answer setting,
set a shorter ring time than that set for the Voice Mail Service (This
also applies to the Call Forwarding Service).
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