There isn’t much difference between an Ethernet cable and your in-house telephone wire (the RJ-11 jack that your phones use even plugs into most RJ-45 Ethernet ports, albeit on 4 wires instead of 8).

This is a multifunction RJ45 network cable tester. It is the design of the network cable (RJ45) test, and telephone (RJ11). It is cheap and easy to use. It works for network, telephone, cable with ...