|You should contact the manufacturers of your PBX for detailed information on how to do this. Not only will they be able to tell you if it can be done, they'll also be able to give you detailed instructions on how to do it, including any/all parts required.|
From what I can see, you don't even know if your equipment is capable of doing this at all.
That's where you need to start anyhow contact the manufacturer or supplier you bought it from.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.