kbc@uts.amdahl.com (Kevin Carney) (01/14/91)
To anybody who can help, I am posting this question on behalf of my uncle. My uncle lives near San Luis Obispo, California and has a Macintosh Plus with the Hayes compatable modem sold by Apple. His brother lives in Belfast, Northern Ireland and has an Atari ST with a modem of an unknown type. They would like to be able to transfer files between their two computers (apparently there is a "Mac" board that fits in the Atari and allows Mac software to be run). This linkup isn't working. It doesn't matter from which direction the connection is initiated, the symptom is the same. The machine which is supposed to answer the phone does indeed answer the phone, but the machine initiating the call never sees carrier detect. I have heard that American modems and European modems operate by a different set of rules, but i've never had any personal experience attempting a telco link from the USA to Europe. Is this true? Could the problem be that that neither modem will ever see carrier detect since the other one will never respond in the required way? If so, does there exist anything like an "international" modem which can operate according to both sets of rules? Kevin Carney Amdahl Corporation kbc@amdahl.com (408) 746-7439
linc@tongue1.berkeley.edu (Linc Madison) (01/17/91)
Seems to me the easiest method to assure compatibility is to get an inexpensive 2400-bps modem. My Supra Modem 2400 (available mail order for about $120) can also accept commands in the "AT" format to use the European standards for lower baud rates. From the reference card, ATB (or ATB0) selects CCITT V.22bis mode at 1200 baud ATB1 selects Bell 212A mode at 1200 baud That means that you may not even need to change modems! Try just changing your dialing string from ATDT011... to ATBDT011.... Just for completeness, AT&P (or AT&P0) selects US/Canada "make/break" ratio for pulse AT&P1 selects UK/etc. "make/break" ratio Be sure to reinitialize any settings you change on your international calls when you make a domestic call, of course! Linc Madison = linc@tongue1.berkeley.edu Disclaimer: I have no connection to Supra, except being a VERY happy customer. These commands are presented as part of the "standard" AT command set, but are not guaranteed to work on other "AT" modems.
johnl@iecc.cambridge.ma.us (John R. Levine) (01/22/91)
In article <16095@accuvax.nwu.edu> lars@spectrum.cmc.com (Lars Poulsen) writes: >>I have heard that American modems and European modems operate by a >>different set of rules, ... Is this true? >Yes. Well, sort of. As noted, 2400bps and higher are the same everywhere except for the various proprietary 9600bps versions that proliferated before V.32 became cheap enough to be popular. For 1200bps modems, the U.S. "Bell 212" and international CCITT schemes are pretty close except for differences in the initial handshake. Hayes modems and most clones have a B command that make the modem switch from the default 212 mode to the CCITT mode. Regards, John Levine, johnl@iecc.cambridge.ma.us, {spdcc|ima|world}!iecc!johnl