switel DCT 577 Série Mode D'emploi page 144

Telephoning
Transferring an external call to another handset
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3-Party Conference
/
☞
Any handset hangs up during a conference call will leave the other
handset still in connection with the external call.
16
During an external call . . .
Press the Menu softkey.
Select INTERCOM and press OK.
Enter the internal telephone number. The external call is put
on hold. When the called handset answers you can
announce the call transfer.
Press the On-Hook key. The call will be transferred.
During an external call . . .
Press the Menu softkey.
Select INTERCOM and press OK.
Enter the internal telephone number.
When the called handset answers ... press and hold down
the star key until CONFERENCE appears in the display.