When you talk to a contact before transferring the call it is called as a supervised transfer. Your initial call to the contact is called as a consultation call or an enquiry call.
In a supervised transfer you can confirm if the contact is present and wants to accept the call.
To make a supervised transfer:
1.Answer the incoming call.
2.Click 
Consult.
3.Use the form that appears to enter the name or number to which you want to transfer the call.
4.When the required match is selected or the number entered, click 
Go. The system places the current call on hold whilst you consult the other party.
•If the other party answers and will accept the transfer, click 
Complete Transfer.
•If the other party does not answer or does not want to accept the transfer, click 
End. Then click 
to take the previous call back from hold.