Busy Connect

John Leong johnleong at research.bell-labs.com
Thu Jan 28 18:38:44 UTC 1999

> "No answer", to me, as an ISP customer would mean
> that there is a broken modem somewhere that is not answering the
> Definitely different than "Busy."

The modem return code, unfortunately is often not precise.  After
dialing, if it gets any voice response, be it some human answering
because of mis-dialed, message from the phone company offering to retry
when line is free, annoucement of "As of <day>, the area code you called
will be change to <XXX>", and finally annoucment of "All circuits are
busy, please retry latter" ... all will result in a "no answer" return
code as the modem expects and not getting the commencement of the modem
hand shake sequence.

All such voice reponses have nothing to do broken modem ... and the last
case is actually a busy condition that cannot be correctly handled by
most modem (the Courier has the capability to return a "voice" return
code ... but cannot, for good reason, tell you what is the nature of the
voice message).

This had been a pain in the rear end to me in my previous project.  I
will be happy to share with anyone my experience with modems ... but
let's take this off line.

Best Regards,
John Leong

Bell Labs Research       johnleong at research.bell-labs.com
4995 Patrick Henry Dr.                  Tel: 408-567-4459
Santa Clara, CA 95054                   Fax: 408-567-4448

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