you can get a rough estimate by dividing the volume of the phone booth by the volume of a quarter, but that assumes quarters fit perfectly into your booth, which they don't.

You don't give the height of the phone booth so I can't determine the volume but you can get an approximation of the number of quarters per inch height of the booth.

Booth volume = 32*32*1 = 1024 cubic inches volume per inch of height.

The quarter has volume $V_q=\pi (0.955/2)^2*0.069 \approx 0.05$ cubic inches

So the number of quarters that will fit into a 1 inch tall booth is $N\approx \dfrac {1024}{0.05} \approx 20480$ quarters per inch of phone booth height.

A better approximation takes into account the fact that quarters are round.

You will only be able to fit $\left\lfloor \dfrac {32}{0.955}\right\rfloor=33$ quarters in a row in the booth.

So per quarter thickness of phone booth height you have $33^2 = 1089$ quarters.

You can stack $\dfrac 1 {0.069}\approx 14.5$ quarters per inch of phone booth height.

So you can fit approximately $1089 * 14.5 = 15790.5$ quarters in 1 inch of phone booth height. A fair bit less than the rougher estimate above.