Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: Dave Levenson Newsgroups: comp.dcom.telecom Subject: Re: Telephone Diverters Message-ID: <10792@accuvax.nwu.edu> Date: 13 Aug 90 02:51:16 GMT Sender: news@accuvax.nwu.edu Organization: Westmark, Inc., Warren, NJ, USA Lines: 43 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 565, Message 7 of 9 In article <10763@accuvax.nwu.edu>, motcid!segal@uunet.uu.net (Gary Segal) writes: > I wrote (in an earlier posting): > >What in the world is "reverse modem detection"? The originating modem > >remains silent, expecting answer-tone from the answering modem? and Gary responds, in part: > Here is a guess ... The device is looking for V.25 calling tone. V.25 and to my statement: > >As far as I know, some fax machines, in some originating modes, > >generate the CNG tone when they're awaiting answer. I know of no > >non-fax modems that would work with the device described above. Gary responds: > All fax machines are supposed to generate calling tone when the > machine dials. If an autodialing fax machine doesn't generate calling > tone (CNG), it is in violation of the T.30 recommendation for fax > machines. Our FAX machine (Brother 200) only generates CNG tones when it is in autodial mode. The trouble is, in autodial mode, if it gets a busy signal or a ring-no-answer, it just reports ERROR and drops the call. Therefore, I generally use it in manual-dial mode, where I can hear the call-progress tones from its speaker. I wait until I hear answer-tone from the far-end FAX machine, and then I press the START button. At that point, the speaker is cut off, and the machine sends CNG tones, followed by the actual data carrier. If I got a silent answer, I guess I'd have to assume its a diverter, and press the START button and hope... Doesn't sound very practical, does it? Dave Levenson Voice: 908 647 0900 Fax: 908 647 6857 Westmark, Inc. UUCP: {uunet | rutgers | att}!westmark!dave Warren, NJ, USA AT&T Mail: !westmark!dave