Making your partners call ?????

[Homer]

Note as well that under the Rule Book, net fouls are the proper responsibility of BOTH officials.

Rule 5-3-3.c.9 gives the referee authority to "determine net fouls".

Rule 5-4-3.b. gives the umpire authority to "determine net fouls on both sides of the net."

The referee has a much better view of net fouls which occur near the referee stand on the ref's side of the net than does the umpire. Indeed, with as many as three players standing/jumping/running around between the umpire and the player committing the net foul, the violation may well not be visible to the umpire.

If you see it, call it. And I see no particular need to wait on the umpire before signaling the call - the umpire might not have seen it and if you coax the umpire into making the first signal on a foul s/he didn't see, what's his response when the coach says, "Which number, ref?"

"Ask the up-ref, I didn't see it" hardly seems a proper response.