If it’s FIOS, then it is probably Verizon. I had my land line at that address from 1983. I got my internet service in 2006, I think by that time it was Verizon. And when my land line service was destroyed by my neatnik renter it was Verizon that said I could not get my land line back, but could buy a 24 hours of capacity backup battery. At some point in the far past it was AT&T or Bell Atlantic or perhaps they were the same. I don’t know if Verizon took one of them over or if I had to use Verizon to get the internet, however, I also have Verizon at another property I bought in 1967, so maybe it was a buyout of the older companies. I don’t like to change things if I don’t have to.
Our landline is with AT&T. It’s more dependable than our cell phones area. When we need support for the cells, it’s the landline we use to call Verizon. Every year I hate cellular more. Every time they make “improvements”, things get worse.