32318ae4_tworking___Firewalls_Tutorials_able_4_Network_Devices_Summary_Function_Purpose
[Device] CSU/DSU [Key Points] CSU/DSU functionality is sometimes incorporated into other devices, such as a router with a WAN connection. [Function/Purpose] 
Translates digital signals used on a LAN to those used on a WAN.
Networking - Firewalls Tutorials
Function/Purpose