Monitoring Channels


I would like to know if it’s possible to monitor the status of a channel with the Busy Lamp Field of my “Linksis SPA 932”. The behaviour i desire is this:

1.- I receive a call.
2.- I Transfer it to a contact (not an extension, but a external phone) that i have stored in one of the SPA-932 buttons.
3.- Once i have transfered, the button associated with that contact remains red until the call is finished so i know if I can call him.

In summary, i want that the buttons of the spa932 associated with a external phone have the samen behaviour than the ones that have an extension of asterisk associated.

Is it possible??

Thanks in advance