Two players are positioned behind the baseline: one on the right, and one on the left. They practice serves, alternating one serve at a time. The basket of balls is positioned between the two servers, at the baseline.
On the other side of the net, one player practices returning the other players’ serve.
He moves side to side, according to who is serving – if the opposite right-side player serves, he positions to return from the right side, and so on.
If the server missed, the returner moves to the other side to receive serve from the other server. They don’t play the point out, just practice serve and return.
Players switch places clockwise, after about 5 minutes.

Note: the drill emphasises return practice and quick reaction and control of the returner.