VTech 15550 User Manual page 46

To make a 3-way conference call
The conference call feature allows one external call to be
shared with two handsets (in intercom). The three parties
can share the conversation and no network subscription
is required.
During an external call
Follow Steps 1 to  in "To transfer an external call to
1.
another handset:" .
. Press and hold on the calling handset to establish
the 3-way conference call.
Note: If either handset hangs up during a conference
call it will leave the other handset still in connection
with the external call.
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:
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