Path: utzoo!telecom-request Date: Thu, 2 May 1991 13:59:29 GMT From: Jon Sreekanth Newsgroups: comp.dcom.telecom Subject: Re: Remote Three-Way Conferencer Message-ID: Organization: TELECOM Digest Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 328, Message 3 of 13 Lines: 51 In article hollands@hale.UUCP (Chris C. Hollands) writes: > The purpose of the device is to be able to remotely use the three-way > conference call feature offered by the telephone central office. > Well, this conceptually simple device is pretty far beyond my > experience level. I think it requires a single-chip computer with a > bit of programming, perhaps some relays, a DTMF decoder and encoder, a > power supply, etc. Thanks in advance for your help. > Note: I saw Larry Casterline's email about just such a device and I am > trying to contact him directly. However, I would still like to build > the device I described above. Thanks. If you've already contacted Larry, that's one good off-the-shelf solution. If you don't mind programming, you can do most of what you wanted with your own modem. Assuming you have a modem in a PC in your office, you have most of the pieces. I think most modems don't have DTMF detectors, but they can generate DTMF. Hayes compatible modems have standard, interrupt driven responses to telephone line activity and to program commands. I don't know the bit locations and such, but it should be possible to do the following: Program a TSR (terminate and stay resident), and leave your pc at work powered up. The modem will sense an incoming ring, pick up the phone, and then hang up. Then it dials your home number (that gets you the security you need), waits, flashes the switchhook, gets another dial tone, and makes the second call. Getting it to hang up after the call is over is a little messier, but once you and the other party hang up, there should be a dial tone after a few seconds, and the modem can sense that to hang up. If you have a fax card based on the Yamaha chip, the chip has a DTMF decoder, so that's a complete solution. I don't know about Rockwell and Sendfax(tm) type chips (anyone know ?). Programming all this stuff might take more time than it's worth, of course. Regards, Jon Sreekanth Assabet Valley Microsystems Fax and PC products 346 Lincoln St #722, Marlboro, MA 01752 508-562-0722 jon_sree@world.std.com