The Picturephone System: Line and Trunk Maintenance Arrangements

The wideband nature of the facilities for Picturephone service introduces a new degree of complexity in the methods used to maintain lines and trunks. Access methods acceptable in the telephone network are not applicable in this wideband network; in addition, testing capabilities are greatly expanded. The Local Test Desk No. 15 and Testboard No. 23 are designed to provide the required access and test capability. The equipments obtain access by means of the No. 5 crossbar system and it is suggested that the article on that switching system be read first. I I . BACKGROUND The objective of integrating the Picturephone service into the existing telephone plant requires that the maintenance arrangements should blend into and be absorbed by existing areas of responsibility in the operating companies. Line and trunk maintenance arrangements consequently are treated separately and distinctly, as they currently are, and they are compatible with the existing arrangements. Figure 1 is a simplified illustration of the existing maintenance arrangements. Lines, in general, are tested on a centralized basis from 645