Walker Headset WTS-501 The New WTS-501 Provides all the features required by installers and repair technicians for line testing and temporary communications in the field. Integrated circuit voice network provides optimum receive and transmit levels and controlled side tone without drawing excessive current. TALK/RING/MONITOR switch conveniently located inside hand grip. Switchable tone or pulse dialing. Tone/Pulse switch located on inside of hand grip. High impedance monitor will not disturb data, conversations or signaling. Polarity Indicator Last Number Redial (31 digits maximum) 10 number memory storage. Memory storage is maintained by 3 Volt Lithium CR 2032 battery. 3 position Volume Control for up to 12 dB of gain. Protection against excessive voltage, transient ringer signals, and direct connection to most batteries and power supplies. Spring loaded reversible belt clip. Cloth covered cord equipped with securely anchored strain relief, modular RJ11X plug, and two five-way test clips. Spade connector cord included. Moisture Resistant 2.5 mm Headset Jack. To purchase a compatible headset