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Date: Sun, 22 Dec 1996 14:25:43 -0700
To: freebsd-questions@freebsd.org
From: Doug Russell <drussell@internode.net>
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>That's *NOT* the correct thing.  What happens when for some reason
>PPP happens to send the sequence '+++' to the modem?  All of a sudden
>it'll drop into command mode and you're screwed.  User-PPP (as well as
>all other PPP/SLIP implementations I've worked with) assumes that you've
>disabled the escape sequence at least temporarily.

You aren't ENTIRELY correct.  If set up properly, the +++ sequence SHOULD
work properly.  a +++ in the datastream won't trigger going into command
mode unless there has been no data sent for a specified delay period.  (See
S12 in your modem's S-Rigister table.  From a Courier HST V/Everthing:  Sets
the duration, in fiftieths of a second, of the guard time for the escape
code (+++) sequence.)  Default is 50 (1 second)).  So, in other words, you
have to not just have a +++ come over the connection, but at least a one
second pause,  a +++ (and only a +++) then another 1 second or longer pause,
in order for the modem to go into command mode.  It is possible, but highly
unlikely.

Of course, this is not the "proper" way of hanging up a modem.  The
generally accepted method (especially with UNIX systems) is to drop DTR.
The modem should be set to at least hang up, if not do a full reset, on DTR
drop.

I have always set my modems this way under DOS, and under UNIX.

Biggest reason with a good old term program in DOS?  It takes MUCH less time
to do a vDTR^ than it does to wait a second, +++, wait a second, ATH.

Later......                                             <Doug>