What is a Telephone WATS line?

Watts line is a dedicated long distance service for government or corporate use. Set fee on unlimited use. I remember them from pre cell days being in service.

It's actually WATS, which is an acronym for Wide Area Telephone Service. Inward WATS is an 800 number or one of its newer cousins. Outward WATS is a line that can place unlimited calls within its service area (the whole country, or just a part of it) for a fixed monthly price.