By default, if you push the Transfer button on a Polycom VVX it will do a Consultive (Attended) Transfer, if you want to do a Blind Transfer you will need to Hold down the Transfer button for at least 2 seconds. It will then give you a menu to choose Blind by using the arrow and neter key on the phone.
If you want to change the default behavior from Consultive to Blind, go to your phone settings, select Basic, select prefereneces and then scroll down to Default Trasfer Type, change the check box to Blind and then press the select button. Press the home button to finish.