In article pB3tk.121173$nD.54050@pd7urf1no,
Tony Hwang wrote:

Back in the dial-up days, I lost count of the times I would
clear a hard short trouble report by removing the RJ11 plug
from the ethernet port in the back of the computer and reconnect
it into the nearby, internal modem IN port.

You mean there are some dumbs who [can't] see the difference
between RJ11 and RJ45?

Oh, yeah. :\

For whatever reason, the customer unplugged the phone cord from the
computer's internal modem IN port. Then, probably fumbling around in
back where it's dark and without a good, solid view, they inserted the
plug into the ethernet port.

An RJ11 plug fits nicely into the 8-pin (usually ethernet) RJ45 jack.
Doing so places a short across the center pins of the phone cord and,
thusly, across the pair, effectively "killing" the phone line. Simply
unplugging the phone cord from the ethernet port/jack removed the short
and restored the customer's dialtone.
--

JR