rfg@hound.UUCP (R.GRANTGES) (10/03/84)
[.] Anything is possible. I have no inside information and could not discuss it if I did. However, you are misinformed on a couple of factual points. First, telephone central offices (plain or digital fancy) do not look for or detect data signals on customer lines. It would be very expensive to modify them to do so - even the new electronic and/or digital variety. If they did, you could always make voice calls and then switch in the modem after a delay (which is in fact what you do now, except you switch in the modem as fast as possible). What the telcos probably want to do is introduce special data lines (perhaps digital) as an improved service to their customers. Then they might lobby to force data users to stop using pots lines (Plain Old Telephone Service). I forgot what the second point was, if any. Dick Grantges hound!rfg
paul@dual.UUCP (Baker) (10/05/84)
Central offices do not and do not need to know if a modem is being used. On the other hand Echo suppressors that are used to prevent you hearing your own voice returned after a few seconds on long lines, need to be disabled for a full-duplex Modem to work. It does this by detecting the answer tone given by the Modem. Note that this is the same tone for all Bell standard Modems. Digital central offices are in no better position to interpret information passed through them. There does seem to have been an interest in the past by phone companies to try and charge Modem users more than voice users. So far none of them have been successful. Paul Wilcox-Baker
steveg@hammer.UUCP (10/07/84)
There is a thing on most phone lines (particularly long distance trunks) called an echo supressor. Part of the 103/212/VA3400 modem protocols is a magic tone to disable these beasties as they alter the signal and echos aren't a big problem in full duplex modems anyway (transmitting and receiving use different frequencies). Steve Glaser (tektronix!steveg)