How would you terminate a T1 line?

Usually T1's are terminated on an RJ48 jack. If the T1 line is provided by a telecom company, a T1 Network Interface Unit (NIU) is often installed with an RJ48 jack. A T1 NIU may also be referred to as a 'smart jack,' a device which allows remote, and on-site, loop up and testing capability, as well as indicator lights for basic fault isolation. An RJ48 jack accepts an 8-position, 8-contact (8P8C) modular connector. It's important to note that RJ48 jacks and connectors are often confused with RJ45 (Ethernet) jacks and connectors, because they may look identical, but RJ48 uses a different wiring standard and a different pinout - uses pins 1, 2, 4 & 5. However, some RJ48 jacks and connectors have a keyed notch on one side.