I see you will have a lot of laughs on the job, not just stress. But truly there should be fines for idiots who abuse the system. Maybe it will have to go the route of the 411 calls - charge per call. If you have an emergency, you'd be glad to pay the $1.50. If you call frivolously, you may call less often.
Or, $5 per call, waived if it is an actual emergency.
Just dreaming, of course, since the fee would be uncollectable from public phones. There's no way they could get away with demanding payment up front before they will listen to the reason for your call. There's also little chance they could talk someone into depositing coins in the phone after it is determined that the call was frivolous. Sigh.