[OFFTOPIC] Detector for modem for driver I want to code

Mike A. Harris (mharris@ican.net)
Wed, 23 Jun 1999 16:53:58 -0400 (EDT)

I'm in need of a device which will connect to the phone line, and
either the printer port or a serial port. The device is to
toggle a pin on the printer port when the phone line is currently
"busy" due to a voice phonecall in place, or an incoming ring
signal. I either want a ready made device, or schematics for
one.

It is important that the device takes all phoneline voltages into
account including on-hook, off-hook, and RING. I am aware of the
voltages, and don't want the 90VAC ring signal on a parallel port
pin. ;o)

It is likely to be a very simple circuit indeed. I just don't
have the time to devel one, and have no idea where to search on
the net for one. I figured someone in this list could point me
in the right direction - either a technical mailing list that
deals with things like this, or some website or another.

What I'm using it for is this: I want to automate my modem to
poll for mail once an hour or so, do a fetchmail and sendmail,
and then to log off. I *ONLY* want it to do that though if the
line is NOT in use currently (I only have one line). Also, if
the modem is allready online, I want my script to just sit idle.
So basically, if I'm not online, and not talking voice, I want my
script to go out for a mail run and then disconnect. To do so, I
need a device to detect if the phone line is not in use.

Someone suggested to me that the modem will not dial if ATX4
command is in the init string, and there is no dialtone. That is
true, but that is not what I want because 1) I have to use ATX3
because I have "call answer" and the modem wont dial out if I
have messages waiting because it can't detect the dialtone - so I
need to force it with X3, and 2) The modem still takes the line
off hook with X4 and looks for a dialtone. I've got my phone
plugged into the modem, and as such, my voice call will get
interrupted by the modem every 30 seconds and I'll get cut off.

So, I really do need this device. Any help would be greatly
appreciated. Sorry for the [OT] posting.

--
Mike A. Harris                   Linux advocate      GNU advocate
Computer Consultant                          Open Source advocate  


Tea, Earl Grey, Hot...




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