A digital subscriber loop carrier system for providing private line service on multi-party lines

To improve multiparty telephone services, a four-channel digital subscriber loop carrier system is proposed. Adaptive differential pulse code modulation bipolar 6-zero substitution line coding, and time-compression multiplexing of speech packets under microprocessor control are novel features of the proposed system. It is believed the design for a digital subscriber loop carrier system outlined will meet the requirements for providing private line service on multiparty lines. The cost of such a system is expected to be less than that required for reinforcement with metallic cables, while providing a comparable level of service