The port on the back of the Apple STB is actually literally a T1/E1 port (even though it looks like TP Ethernet), with a Brooktree Bt8069-Series Line Interface

The port on the back of the Apple STB is actually literally a T1/E1 port (even though it looks like TP Ethernet), with a Brooktree Bt8069-Series Line Interface Unit chip inside for a T1/E1 interface! I'm not sure if there were T1 adapters for DSL etc back in the day, but I guess that's plausible (before the computer world won over the telecom world there were a lot of weird standards that looked like they would be adopted - ATM anyone?) edit: Apparently T1 started being carried over HDSL which is probably what was being used here https://www.arcelect.com/HDSL3698.htm https://www.arcelect.com/HDSL3698.htm