The fax feature in my HP Officejet 7410 works with the phone jack
I initially plugged it into, but when I moved the printer to a
different phone jack, it kept insisting the phone was off-hook. My
temporary solution was to move the Officejet back to the original
position, but I’d rather have it in the second location. Do you have
any idea what the problem might be at the second jack and how to fix it?
The most likely explanation is that you’re using a standard
telephone cable. The solution is to replace it with the one HP
provided, or get a new one with the right cabling. Not so incidentally,
the same issue can crop up with other AIOs designed for worldwide use,
and it’s caused by having to accommodate different phone systems.
The RJ-11 connector has six pins. In standard phone cables, the
middle four-pins 2, 3, 4, and 5-are connected, with 3 on one side
connected to 4 on the other, and 2 on one side connected to 5 on the
other. In the U.S., a jack wired for one phone line will use pins 3 and
4. If there’s a second line, it will use pins 2 and 5. The phone cable
that comes with the 7410 for use in the U.S. uses only pins 3 and 4 on
both sides. To accommodate European phone systems, the fax circuit
inside the AIO needs to connect pins 3 and 4 to pins 2 and 5. If you
use a standard four-wire cable on a two-line jack in the U.S., this
shorts the phone lines and creates problems. The fix is to use a cable
that connects only pins 3 and 4.
(More tips from PC Magazine)