BY TURNING ON 906 and 907!!!!

The "PBX" isn't a mystery. Get the vendor to give you the password and the programming software that is your right to own with the system. It is not protected in any way and you can mess it up, but not if you're careful. MAKE A BACKUP before you start.

Point out to the "administrator" that you're all on the same team and either they make the change or you will.

Geeze, this is telephony, not rocket science.

Carl