Newsgroups: sci.electronics
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Modular Telephone Connector
Message-ID: <1988Sep22.060244.3959@utzoo.uucp>
Organization: U of Toronto Zoology
References: <4063@enterprise.UUCP> <1988Sep16.171228.16442@utzoo.uucp> <14054@ninja.UUCP> <17723@glacier.STANFORD.EDU>
Date: Thu, 22 Sep 88 06:02:44 GMT

In article <17723@glacier.STANFORD.EDU> jbn@glacier.UUCP (John B. Nagle) writes:
>     Tip/ring polarity doesn't matter for nonelectronic dial phones, but
>most Touch-Tone (tm) dials need the right polarity for their power.  
>This is certainly true of the traditional Western Electric product.

No, only of the *old* Western Electric product.  The very early Touch-
Tone dials needed specific polarity.  All the modern ones, even from WE,
have a diode bridge that eliminates the problem.  I'd be surprised to
find any modular-jack phone that cared, since reversals are normal in
modular wiring, but one might find an occasional oldie converted to
modular jacks unofficially.

For that matter, I seem to recall seeing mention that some old dial
phones worked better with one polarity than with the other -- with
annoyances like slight bell noises during dialing if you got the
polarity wrong -- but I've never confirmed this personally.
-- 
NASA is into artificial        |     Henry Spencer at U of Toronto Zoology
stupidity.  - Jerry Pournelle  | uunet!attcan!utzoo!henry henry@zoo.toronto.edu