MOD-AT2 Module is designed to protect standard phone lines connected to computer modems, telephones, pay-per-view ports, etc. It will also protect DSL lines (ADSL, G.Lite) going into the DSL modem. The MOD-AT2 module will protect a single phone line using an RJ-11 (2 wire) cord or a dual phone line using an RJ-14 (4 wire) cord.