Just to add a note to the great tips from Chris (+5 C-Man!)
Onhook Call Transfer
Modifications to the Call Transfer feature add the onhook (hangup) action as a possible last step to complete a call transfer. The Transfer On-hook Enabled service parameter, which enables onhook call transfer, must be set to True for onhook call transfer to succeed. If the service parameter is set to False, the onhook action ends the secondary call to the third party.
In the existing implementation, if user B has an active call on a particular line (from user A) and user B has not reached the maximum number of calls on this line, the Cisco IP Phone provides a Transfer softkey to user B. If user B presses the Transfer softkey (or Transfer button, if available) once, user B receives dial tone and can make a secondary call: user B dials the number of a third party (user C). Cisco CallManager provides a Transfer softkey to user B again. If user B presses the Transfer softkey again (or Transfer button, if available), the transfer operation completes.
With the new onhook call transfer implementation, user B can hang up after dialing user C's number, and the transfer completes. Both the existing and new implementations work in both the case of a blind transfer (user B disconnects before user C answers) and also in the case of a consult transfer (user B waits for user C to answer and announces the call from user A).
The previous implementation remains unchanged: user B can press the Transfer softkey twice to complete the transfer.