integrated service unit (ISU)

An Integrated Service Unit (ISU) is a unit formed by a combination of Channel Service Unit( CSU) and Data Service Unit( DSU).

An Integrated Service Unit (ISU) forms the interface between the customer's digital telephone connection and the network operator's digital telephone network. The ISU unit connects a customer's digital telephone equipment to the formats used by a telephone network by adjusting transmission protocols, electrical levels, and physical connections.