ECN Forum Forums General Topics of the Trade Voice - Data - Video Discussion Plain old telephone line

I recently heard a term for a regular tel line. For example a line I would use for a fire alarm panel as opposed to a line connected to a PBX or whatever. I want to use the term but can not remember what I heard. It was sort of like plain old tel line. It may have had an acronym. Any one know hwat I may have heard?