Indeed ISDN was amazing for its time but Ma Bell and her successor ILECs were way too proud of it so in the end it went nowhere and never made them all that muc

Indeed ISDN was amazing for its time but Ma Bell and her successor ILECs were way too proud of it so in the end it went nowhere and never made them all that much money. If they had gotten out of their own way when the internet came around they could have charged a small monthly fee to upgrade to a "digital phone line". Lots of people would have switched.