Austdac AM7021 Installation guide

Hello, I've analyzed the Maintenance Manual for the Mine Telephone 821301/302 AM7021. This manual provides detailed information on the telephone's circuit operation, including its permissible design, power specifications using two 12VDC batteries, and unique features like a full wave bridge rectifier and solid state paging system. I'm ready to answer any questions you have about its maintenance or technical aspects.
What type of batteries are used?

What is the phone line impedance?

What is the paging sensitivity?

What is the maximum speaker output power?