What's the communication pad for?

Answer:

Digital trunk board (divided into 2B+D and 30B+D), is through the 1 2M optical fiber data, provides 30 voice channels, equivalent to 30 analog telephone lines, the general situation is the use of large enterprises, hotels, and engineering units; E&M simulation of relay board is mainly used in the networking, analog relay.The above is basically the switch, the general needs of the relay plate.

The trunk board is equivalent to what we call an outside board, mainly to connect voice lines provided by carriers. The relay board is generally divided into analog relays (home lines);