Path: utzoo!utgpu!watmath!clyde!att!rutgers!cmcl2!yale!husc6!ogccse!blake!uw-beaver!rice!sun-spots-request
From: ultra!shj@ames.arc.nasa.gov (Steve Jay)
Newsgroups: comp.sys.sun
Subject: Re: SunOS 4.0 dialin/dialout
Message-ID: <8812272326.AA20714@macduff.ultra.com>
Date: 5 Jan 89 05:53:51 GMT
Sender: usenet@rice.edu
Organization: Faculteit Wiskunde & Informatica, Universiteit van Amsterdam
Lines: 32
Approved: Sun-Spots@rice.edu
Original-Date: Tue, 27 Dec 88 15:26:51 PST
X-Sun-Spots-Digest: Volume 7, Issue 89, message 5 of 11
X-Issue-Reference: v7n67

In v7n67, Charlie Dennett (dennett@kodak.com) describes a situation where
a modem in his office can't dial successfully to the modem connected to
his Sun, but calling from home works.

This may be a strictly modem/phone-line weirdness, having nothing to do
with the Sun.  Some modems have a feature called "call-progress detection"
whereby they listen on the phone line for ringing, busy signals, and dial
tones so they can give you the progress of the call.  Unfortunately, some
of these modems get confused if they hear the answer tone BEFORE hearing
at least one ring.  Some newer phone systems will ring the called phone
before they send the ring sound to the caller.  So, particularly on
internal calls where there are mimimal delays, the called modem may answer
and send its tone before the calling modem has heard a ring.  Some modems
will not recognize the answer tone in this situation.

The timing of calls which come in from outside the local phone system is
such that the caller always hears at least one ring.  This may explain why
you can call from home, but not from your office.

Check the manual for the calling modem...it probably tells how to disable
the "call-progress" feature.  With that feature disabled, the office ->
Sun connection may start working.

I got this information from article <505@drilex.UUCP>, dated 20 Mar 88, in
comp.dcom.modems, sent by {harvard!axiom,linus!axiom,ll-xn}!drilex!dricej
(Craig Jackson).

Steve Jay                       domain: shj@ultra.com
Ultra Network Technologies	Internet: ultra!shj@ames.arc.nasa.gov
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