The Fluke Networks TS23 Pro telephone test set, available with various line cord connectors to suit specific applications, detects dial tone and polarity; places and receives calls; indicates line voltage and current; has a two-way, adjustable-volume speakerphone for hands-free conversation during testing of telephone lines; monitors lines without disrupting service; and stores up to nine 23-digit telephone numbers which can be speed-dialed via the keypad. It provides tone or pulse operation. The test set has two basic modes of operation: talk mode for off-hook operations including verifying dialing and receiving calls, and monitor mode for on-hook operations including checking for an idle line, listening for line noise, and measuring DC voltage on the line. In monitor mode, the test set provides a high impedance coupling to monitor lines without disrupting service. This test set meets IEC (International Electrotechnical Commission) safety standard 61010-1:2010 and is rated for CAT I installations to 300VDC, which covers equipment on circuits not directly connected to mains. It passes a 20' (6m) drop test and is Ingress Protection certified IP64 for protection against dust and splashed water. The high-visibility glow-in-the-dark keypad has 12 standard dialing keys including star and pound, and function keys to store, recall, and redial numbers and to pause for accessing a second dial tone when dialing through a PBX (private branch exchange), among other functions. It has six dual-color LEDs that indicate talk mode, polarity, mute, voltage (VDC), current (mA), and battery status. The voltage LED indicates five different levels of voltage and an alarm sounds to indicate voltage greater than 140VDC. The current indicator flashes red for less than 23mA and flashes green for greater than or equal to 23mA. The test set can be programmed to turn off automatically after one to 60 minutes (default setting is two minutes) of inactivity to conserve batter