bob wrote:
I have 4 analog land line service from comast. The 4 lines come out of
two RJ11 jacks on the cable modem.

I have a multi line phones (att 1040) that accepts 4 lines via two RJ11
jacks.

This should be simple, just connect two RJ11 jacks from the modem to the
two RJ11 jacks on the phone.

Except the modem and the phone is far apart with an in-wall RJ45
(ethernet) cable between them.

Is there an adapter that would take the 4 lines from two RJ11 jacks and
convert them to RJ45 jack (that happens to have 8 conductors, or 4 pairs
of lines)? If not, what is an accepted way to make this adapter myself?

I can cut one end off an ethernet cable, and also cut off the ends of
two RJ11 cables and then solder the wires together. But I'm hoping for a
more elegant solution; otherwise I would have to make two such Y cables
one at the modem end, and another at the phone end.

There's a Frys electronics store nearby; is that the best store to find
phone wiring accessories? I live near seattle.

At the risk of stating the obvious...
If you accidentally plug in an ethernet connection and the phone rings,
you might not be happy with the result.
Sure, you're never gonna do that...right!!!