The TS25D features data lockout and lockout override, and a large LCD. Caller-ID and Call Waiting Caller-ID Amplified speakers for hands-free monitoring Data lockout and data lockout override Tone generator for wire identification Talk battery to power voice conversation on dry (non-powered) lines Easy to read oversized liquid crystal display This feature-rich test set is a necessity for a variety of installs. The TS25D Test Set features data lockout and lockout override, making you completely safe in talk or monitor mode. The DSL/POTS filtering technology allows you to safely draw dial tone without downing DSL. A built-in analog tone generator simplifies wire identification with a probe. An amplified speaker makes monitoring the line hands-free, so you can keep working. The talk battery function provides voltage to carry voice conversation on non-powered pairs. All in a compact unit with an oversized robust liquid crystal display (LCD) that makes the intuitive, common-sense menus easy-to-read and use.