Alcatel Optronics has demonstrated the simultaneous transmission of more than 15 million voice circuits on a four-fiber- pair system that uses wavelength division multiplexing. It expects the advance will provide a fourfold increase in the capacity of undersea networks. Alcatel transmitted 32 channels, each at 10 Gb/s, on a single fiber over 6150 km. Researchers will evaluate the transmission distance and performance parameters to prepare for the introduction of high-capacity submarine networks for bandwidth-intensive services.