What is "the phone call"?
Here at our farm, Calathora, we've enjoyed having the best man ride up on a horse and announce the bridegroom's coming, and then the bridegroom rides up. The starting point is a quarter mile down the lane and "the phone call" is simply Michael B.'s way of alerting the guys that IT'S TIME!!!!!
On a side note, the cell phones weren't working at the rehearsal, so we substituted waving a red handkerchief - worked great!!