Residential ISDN was very rare in the US. I rented a house in the 90s with a few fellow nerds and we got ISDN in our house, but it was definitely expensive (an

Residential ISDN was very rare in the US. I rented a house in the 90s with a few fellow nerds and we got ISDN in our house, but it was definitely expensive (and required a network terminal device) and you always had to be routed to a specialist at the phone company if there were any issues, since most of the support people had never heard of it.