Notice: Please check if the mute function is turned on when you use it. There are many customers who do not know they have turned on the mute function. No sound when speaking, they think our products are broken, and then return or complain about us. We said particularly wronged.You can use the conversation between the inside and out side of the window for the customers' evaluation of the salespersons, and for the supervisor's evaluation of each window. 1.Usage: the bank staff use the master station to talk with guests. and the guests use the substation can talk with bank staff as well. 2.Installation: the master station is installed in the working place and the sub station out of the working room. Just one wire connection between the master station and substation. 3.Application: bank, stock office, hospital, post office, box office, toll station, etc. Functions and Features: 1)Hands-free two-way talkback with full automaticity, microphone is clear for both side; 2)Microcomputer controlled circuit with squelch function, can thoroughly solve echo and squeal problems; 3)Adopts high-powered mic, elegant appearance, the voice is lifelike and clear; 4)Easy installation, there is only one wire for master station and substation connection. 5)Volume of master station and substation can be adjusted separately. 6)With recorder jack, can output both route's sound and signal. 7)Mute function for master station and substation. Specification: - Power Adapter: Input AC 110V 60Hz US Plug. Output DC 12V 1.0A; - Desktop Unit Dimensions: 153*79*41mm; - Wall Mount Unit Dimension: 80*20mm Package Includes: 1 x Dual-way counter interphone; 1 x External speaker; 1 x Power adapter; 1 x English manual; 1 x Double-sided tape;