AT&T SYSTEM 25 Manual page 117

Multiline
Transferring a Call
1
Press
The light next to the button of the held call
Dial the other party's PDC or press
2
NOTE:
button next to the winking light. Then return to Step 1 and continue.
3
If you do not want to announce the call, simply hang up. Otherwise,
announce the call and then hang up to complete the transfer.
NOTE:
winking light to return to the held call.
Single-Line
Transferring a Call
1 Press the switchhook.
2 Listen for confirmation tone and dial tone.
3 Dial the other party's PDC.
NOTE:
the held call. (If you hear dial tone, press the switchhook once more.)
4 If you do not want to announce the call, simply hang up. Otherwise,
announce the call and then hang up to complete the transfer.
NOTE:
return to the held call. (If you hear dial tone, press the switchhook
once more.)
2-104 Voice Terminal Features
and listen for dial
[TRANSFER]
If you misdial the number, return to the held party by pressing the
If the called party does not answer, press the button next to the
If you misdial the number, press the switchhook twice to return to
If the called party does not answer, press the switchhook twice to
tone.
winks intermittently.
a line button, for example,
[DSS].