Credit for this one goes to Tim VonDerHaar. I cannot take credit for it, darn. Anyway, I just want to document it here so I'll have a place to look it up next time I want to use it.
Here's the scenario. While the 3CX Windows Phone (v12) or 3CX MyPhone give the user an easy way to manage the Shared Park 'slots', in the real world I find many users just want to be able to do things from their phone and not bother with the computer. I have used provisioning in many cases to define Memory/BLF keys as Shared Park slots and for phones that don't have Memory keys we have taken one or two unneeded Line keys and provisioned them as Shared Park slots.
All this works fine. Then we get to the situation of what to do with cordless phones that don't have all these extra, available buttons to act as Shared Park slots. Now what. This is where we get creative. This works in both v11 and v12.
Create a phantom extension(s) for each Shared Park slot you want to set up (i.e. - ext 500 = SP0; ext 501 = SP1, etc.) In the Mobile Phone Number field enter a value SP0, SP1, etc. Set the Forwarding Rule for the Unregistered state to Send to My Mobile Number. Voila (or Wahlah as I have often read).
Now the call answerer can use whatever method they like or can do to park a call. The roamer that has gone out into the plant and picked up one of the available cordless DECT phones, upon hearing over the PA system that they have a call parked in exit 501, can just dial extension 501 and they will have the parked call.
Again thanks to Tim VanDerHaar.