They had T1 and ISDN at least since the 70s. The landline is special because laws require a line-powered phone system that can survive outages. It's a minimal

They had T1 and ISDN at least since the 70s. The landline is special because laws require a line-powered phone system that can survive outages. It's a minimal and reliable layer of infrastructure which still makes perfect sense for people with limited communications needs.