It seems that there is a lot of incorrect information floating around about T1 extensions, like:
you can extend a T1 cable using a single Cat.5e or Cat.6 cable – WRONG!

T1 circuits are not like a normal data circuit on a network.

If you are extending the T1 and want to use Cat.5e or Cat.6 cable then you must run two (2) cables.

One cable for the transmit and one cable for the receive.

THE CABLE CAN ONLY EXTEND UP TO 50 FT.

You can use a two (2) pair individually shielded cable, specifically designed for the T1 circuit, up to 300 ft.

Take a look at this document for some of the tech details —-> T1 Specifications

Let’s sharpen our skills and get things right!