Got all three of my neurons working together and here's what they came up with,

User fees for high caller volume. Say the first 100 calls per day are covered by the base rate, then callers must pay 1 cent per call. This would not be a significant burden for legitimate business as each call must have a value of more than 1 cent.

What could go wrong?

Where did I get 3 neurons you ask, conjugal visits and fertility drugs.