Ralph.Hyre@IUS3.IUS.CS.CMU.EDU (11/12/88)
I have two lines at our residence, and I'd like to be able to improve the
level of service available via our instrument(s).
We have pulse only service because its cheaper, and none of the custom
calling features. If I could build an interface between our two lines
and some of our intruments (that would provide a psuedo dialtone and
other features)
line 1-----Apple Cat Modem #1---[audio/phone interface]--instrument(s)
+-[switching network]
line 2---- Apple Cat Modem #2-+
The computer would need to detect an off-hook condition (change in
resistance?) on the instrument and provide an 'internal' dialtone.
It also needs to send the 'ring' voltage (48v?) to the instrument when an
acceptable incoming call is being received. (I imagine adding a call
screening feature to the system sometime in the future.) [I would leave one
instrument connected directly to the phone line as a backup in case of a power
failure or other system problem.]
So, I'm looking for plans for some additional hardware to accomplish this.
For example, will the Radio-Shack book 'Understanding Telephone Electonics'
give me enough info to accomplish this, or is it too out of date already?
Thanks.