TS25D battery door with belt clip. The TS25D Test Set features data lockout and lockout override, making you completely safe in talk or monitor mode. Includes DSL/POTS filtering technology and a built-in analog tone generator. The Talk Battery function provides voltage to carry voice conversation on non-powered pairs. Also includes Caller-ID and Call-waiting Caller-ID function. Large LCD makes the intuitive menus easy-to-read and use.