Why would you assume everyone using a phone card to call Mexico is an illegal?
You don’t. Use a little common sense.
He’s saying you take the normal volume of calls to mexico on a normal day and compare that to the increased calls last night. One could estimate that the calls over and above the normal amount are all mexican nationals. Then subtract out the number of green cards issued to mexicans. The remainder would approximate the number of illegal mexicans in the country right now. It wouldn’t be a very impressively accurate accounting, but it would get you in the ball park.
Why do I have to explain this? Are you playing dumb, or are you just stupid?
Actually, as explained by others, I wasn't. I am only assuming YOU are illegal (by your reaction).