EF-701M 4-Wire Interface with Call Signal

EF-701M 4-Wire Interface with Call Signal, Matrix-to-Partyline

The EF-701M interface converts a single channel of standard or TW
partyline intercom to four-wire audio, while also converting call
signals to RS-422 data (and back). The resulting four-wire audio plus
RS-422 data can then be sent t...