Stop paying your power bill or your internet bill and find out
They will cut you off when the time comes, but it can sometimes be surprisingly long. And they will put a lien against the property, too.
In my case it was their fault. I configured automatic payments and they migrated their online system and subsequently dropped my data for payments. Still, they were ruthless about it.
What I've usually seen is they threaten to shut you off with very strong wording, and then continue to threaten you for 3-6 months before they bother to send someone out.
This was a common occurrence that people referred to as 'brown billing' because the shutoff notice had a brown header instead of the green header on your regular utility bill.