The following pages and posts are tagged with

MRCS-ATSN Page Dispatcher/Operator Telephone board / Electronic Speech Telephone Network board (ASTN)
MRCS-Candlestick-Mic Page An electret replacement for a telephone headset carbon mic
MRCS-Morse-Code-Buzzer Page Morse Code Buzzer Board
MRCS-RelayBreakout Page Breakout for OMRON style DPDT relay

You are free to download these files and make your own boards, or you can purchase bare boards or assembled and tested product from Model Railroad Control Systems.