Dual-way intercommunication: Two-way voice window intercom counter interphone adopts auto dual-way intercommunication technology,automatic indentification of processing speech signals during a call dose not require any action. | Host & Extension: Both the main unit and the extension have 78.74IN wire speaker and high-sensitive microphone, and the volume can be adjusted separately. | Sound clear: Inside & Outside Volume Adjustable,CallToU Window Speaker system has a top-quality speaker and high-sensitive microphone; The voice from CallToU Window Intercom system is clear and natural. | Wide Aapplication Scenario: CallToU window speaker can be used in many workplaces, such as bank windows, ticket windows, hospital windows, bank windows, glass windows, counter windows, etc | Recording: There is a recording jack that can be connected to recording equipment, which can work continuously and clearly for a long time.Realize two-way recording conversion.