In data connectivity, the Z-End (also called Z-Loc) refers to the position of the location or network of the customer on a telecommunications circuit, as opposed to the A-end (also called A-loc), which refers to the location or network of the carrier.

The position of each point — or letter — on the circuit can be physical or logical, such as a facility or a room within a facility, or a connection to cabling or equipment. The terms Z-end or Z-loc (or any other letter indicating a point on a telecommunications circuit) may be seen on new circuit orders, customer or carrier trouble tickets, and circuit disconnect orders so that field technicians can easily discern what point to work on.