I think it's a little complexer than this.
You have to answer the call and send a DTMF code to the key.
In most VOIP doorphones, you can choose any DTMF code you want to open the door.
I you take for example the * code, you answer the call from the doorphone and push *. What's the difference with answering the doorphone call and push a BLF to open the door? You don't gain any time and loose a BLF.
I would go one step further. I want the possibility to put a macro behind a BLF.
But it's only usefull in this scenario (for a doorphone at least, there coulde be much more interesting applications for this):
- the doorphone rings and you have a visual view on the door
- by pushing a BLF with a macro, the call is answered, DTMF code for opening the door is sent and the call is ended
If you can't see the door and see who is standing in front of it, you have to answer the call anyway...
Best,
Jos