In fact the pulse contacts are short circuited by the number exclusion logic. The dial turns, but a zero can't be dialed as the first digit.
Otherwise, a call can be made but the transmitter won't be enabled until the money is cashed.
The system had a number of imperfections:
-the owner (innkeeper) was charged by the tel. co when a patron misdialed, but dialed a valid number and the called party answered. In this case the caller would hang up without paying the money.
-it could be cheated by pulling the plug of the phone, and dialing any 3 digits. This would do nothing in the exchange, but activate the number exclusion system in the phone, which is purely mechanic and not electric. Then plug in and dial 0081xyz for time and temperature in Tokyo, just because you thought the innkeeper charged too much for the beer you had.
-with the introduction of a time limit for local calls in the mid 1970ies these phones became obsolete, because there was no time control for the 8 minutes interval.
These phones were really expensive and the owner could not make any money with them, as the charge cashed was exatly the amount that was billed by the tel. co. It was purely customer service to provide one. Unless a patron might come in for a call and have a drink with it...