Has anyone been involved with circuits to take a phone line off
hook and then dial a number on command from the micro? In
general, the parts I'm still researching are:

- Detect if the phone line is already in use without disturbing
an in-progress call
- Go off-hook and dial a number (suggestions for the tone
generation part?)

The device/phone line connection should be a pre-approved DAA. We
don't want to jump through all those hoops ourselves unless
there's a big cost savings at the end.

Low cost is very important. I'm trying to avoid having to
purchase any of the available OEM modem modules or the stand
alone dialers that I've found so far.

A modem built up from the Silicon Labs Si2400 chipset runs around
$21-$27. The Cermetek modem modules are around $35. We don't
really need a true modem for the information we need to send. It
seems like it should be possible to do a much simpler dialer for
half to two-thirds of those costs.

Thanks for any reasonable suggestions,

Tim

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