Change Paging Extension number

Hello All,

I searched the web but didn’t get an answer of value.
I want to change the extension number for paging to something other than 800.
A new system is being installed and they want to maintain the existing extensions and as you can guess, one of the extensions is 800.
I’m not seeing an option to change it, I looked under feature Codes and paging options.

Currently running PBX Firmware: 1.818.210.58-1