The TRA-223 tone-adapter is a simple way to remotely control radio base stations. The TRA-223 can be used in conjunction with all Telex analog consoles, or other manufacturers' consoles that use the industry-standard sequential tonekeying format. Base stations can be connected to the distant remote control console(s) by any voice-grade transmission medium--microwave link, a leased telephone line, or a twisted-pair 600-ohm line, and are capable of decoding the PTT and Monitor function tone sequence. The TRA-223 also features a front panel dip-switch that allows you to select various options, such as two or four-wire line operation along with full duplex.