... USB Telephone Recorder 1,high-impedance recording 2,Accurately judge the channel status 3,Supports AGC 4,FSK, DTMF code 8-channel Telephone RecorderTelephone recorder ... audio, radio and carrier phone. GXUSB-R telephone recorder records with clear tone quality, is easy ... power, railways, oil, ports, transportation and other conducting control centerOffering telephone recording as evidence for government ...