I'm not quite sure what you are asking so I'll give an answer for what I think you are asking
If you mean sending 2 phone lines and a network connection through one cat5 wire then yes that is possible.
Standard phone lines only use 1 pair of wires and 10/100 network only uses 2 pairs. That would fully utilize all 8 pairs of the cat5
10/100 ethernet only uses leads 1,2,3,6. Just choose 4 wires and put the head on so that each wire is in the correct position, 1,2,3,6. When looking at the cable head with the metal connectors up the numbering goes 1-8 from left to right.
The phone line only needs 1 pair. Just choose any 2 wires and put the head on so that the 2 wires are occupy the center 2 slots on the head.
And make sure you get the same colors in the same order at both ends for each head, obviously.