On Fri, 19 May 2000, W. Sierke wrote:

> It has always been my experience that a modem will abort making a
> connection, from the time the ATD command is issued to the modem, until the
> 'CONNECT' message is issued by the modem (CD signal raised), if any
> character is issued to the modem. I've never tested it to the extent of any
> other type of transmission (BREAK, mis-framed characters, invalid start
> bits, etc). Neither have I investigated whether in fact any commands are
> provided to disable this behaviour.
8< snip...

It's correct and documented in most of the older modems - you know, old
enough to have had documentation to begin with.  You are also correct that
the escape sequence is used to gain control of an established connection.
If your modem has decent docs, they will confirm this; if not, a quick
check of the docs for modems that HAD complete docs will do.  The
implementations are almost all very close.  In fact, I believe this even
extends across the Hayes AT and USR command sets style modems.

Dale