What is a CSU DSU used for?

A CSU/DSU (Channel Service Unit/Data Service Unit) is a hardware device about the size of an external modem that converts a digital data frame from the communications technology used on a local area network (LAN) into a frame appropriate to a wide-area network (WAN) and vice versa.Click to see full answer. Keeping this in view, what is the function of a CSU DSU?A CSU/DSU (channel service unit/data service unit) is a digital-interface device used to connect data terminal equipment (DTE), such as a router, to a digital circuit, such as a Digital Signal 1 (DS1) T1 line. The CSU/DSU implements two different functions.Also, are CSU DSU still used? My understanding is that CSU/DSUs are no longer used anymore for modern equipment because cable connections like Ethernet come with fixed bit rates. Also, what is the difference between CSU and DSU? A. A CSU/DSU converts analog signals from a router to a leased line; a modem converts analog signals from a router to a leased line. A CSU/DSU converts digital signals from a router to a phone line; a modem converts analog signals from a router to a phone line.Which port in a Cisco router is used to connect to a CSU DSU? serial port