FT3C is a digital lightwave transmission system designed to operate in both intercity and metropolitan environments. Using wavelength-division-multiplexing, three 90 Mbit/s signals are placed on a single-fiber pair, providing over 240 000 voice circuits in a lightguide cable containing 144 fibers. The nominal operating wavelengths are: 0.825 μm, 0.875 μm, and 1.3 μm; GaAIAs lasers and Si-APD's are used for the short wavelengths, while LED's and p-i-n's are used at 1.3 μm. The terminal design provides interfaces for DSI, DSIC, DS2, and DS3 signals. Emphasis has also been given to features important in operating in unattended offices: performance and alarm reporting, status reporting, and remote control of protection switching. The first applications of the FT3C system are planned for the Northeast Corridor route of AT&T Long Lines and the North/South Lighwave Project in Pacific Telephone. Service for both routes is scheduled for the first quarter of 1983.