Back in the day, everybody ran on analog telephone lines - every home, every apartment, every business, every government office, every charity, everybody - everywhere!
And while most businesses have shifted to more modern telecommunications options, there are still
millions
of POTS lines in use right now, many long forgotten but being paid for month-after-month. PLUS their costs have increased significantly since POTS are no longer regulated as standard phone service allowing carriers to charge high rates along with passing on service costs directly to customers.
Many industries like insurance, healthcare-dental, and legal are very fax-centered. Of course, government from federal agencies to state and local entities are quite analog-centered as well - especially public safety systems.
But wait! Don't forget the millions of credit card terminals, off-brand ATM kiosks, and elevator telecom systems that rely on analog communications in cities and towns all across this country.