[Coco] Telephone System

johnmarkmelanie at gmail.com johnmarkmelanie at gmail.com
Sat Apr 27 20:53:43 EDT 2024


All,

I just made a simple phone system. No dial tone, no dialing, no ring, just
talk.
I can be the switchboard operator and connect two devices.
I can allow 1 to perhaps 4 simultaneous calls on separate circuits (not a
party line).
Some modems can be made to connect without a dial tone in either answer or
originate mode.

Hayes Compatible Modem AT commands
# find the value of register 14
AT S14?
Clear bit-7 of the S14 register for Answer Mode
Set bit-7 of the S14 register for Originate Mode
# Set register S14
# Example
AT S14=0
AT S14=255
# Use AT H0 to hang up
# Use AT H1 to grab line
# Originate Call
N=(AT S14?)
AT S14=(N | 128) H1
# Answer Call
N=(AT S14?)
AT S14=(N & 127) H1
# Hang up call
AT H0

# Use AT +MS=0,,, for 300 baud (This is a guess)
AT +MS=0

John Mark Mobley




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