OK then.

For an old-style analog phone, you need only one pair between phones - in the old days, they were green and red, known in phone company lingo as "tip" and "ring" respectively. This was from the plugs that operators would plug into switchboards in the old-old days 100 years ago.  ("red = ring")

Ethernet needs only two pair (four wires). So, in a 8-wire 10BaseT plug, you have eight wires (four pair) you can run. You could run analog phone on one pair, Ethernet on two more pair, and still have a pair left over.

I'd get Cat5 eight-wire (four-pair) cable to do a run these days.