Paul Kranenburg <pk@cs.few.eur.nl> said:
> I never did do anything with that note to find which change caused
> this, but:  the last kernel I have that does not make the modem
> hang up immediately after it establishes a connection is:
> "NetBSD 1.2C  compiled on Feb 7, 1997".  

Hmm, in my case the modem never gets so far as to establish a
connection - it never even goes off-hook.  I suppose it could still be
the same bug though, causing different symptoms in different modems.

> Sometime after that date but
> before the version was bumped 1.2D,  the "spurious echoing" bug must
> have crept into the system.

For your information, I have just submitted a PR: kern/6502.
It includes a proposed fix.
-- 
Andreas Gustafsson, gson@araneus.fi