Jethro wrote:
I hate to ask this question - as I expect the most logical answer is
'it could be anything'. But since the repairman can't get here until
Thursday, I thought I would throw it out to see if anyone can suggest
something.

It seems my 4 house phones were all working just fine this morning at
10AM. The this afternoon, I discovered that there is a horrible
'buzzing' or 'humming' kind of sound on the line that renders
conversation impossible, and in fact my dial-up is non working as a
result as well.

The buzz is almost certainly electrical.

Flip off all circuit breakers. No buzz?

Turn 'em on one at a time until the buzz returns. Find the device on that
circuit that's the culprit.

It could be a bad florescent ballast, a bad CFL bulb, a motor (like on the
fridge), an electric clock, almost anything.

If, however, turning off the whole house does not remove the buzz, I'm
stumped.