The MOD-FE1 optical fiber modulator and demodulator is a high-performance E1 optical fiber modulator and demodulator. It modulates a framed or unframed E1 data signal directly onto single-mode or multimode optical fiber and transmits it into an optical cable line. At the other end of the optical cable, the optical signal is demodulated into a framed or unframed E1 data signal. The E1 port can be directly connected to the E1 port of image, data terminal, multiplexer, switch, and router WAN port, and can be used to form a dedicated network or to connect to a wide area network.