Some Transmission Characteristics of Bell System Toll Connections

Many systems engineering studies require detailed knowledge about transmission performance and transmission capabilities of the Bell System plant. The need for such information exists both for specific parts or building blocks of the network and for built-up connections between subscribers. A system-wide survey of noise and loss on toll connections was undertaken in 1962.1 The results of this survey found an important application in the setting of new over-all objectives for background noise.2 A similar survey was undertaken in the summer of 1966. It is our purpose to describe this connection survey and to give its results. Present transmission performance of built-up toll connections is given in terms of distributions of noise, loss, and phase jitter. Furthermore, the results include distributions of time to connect, and the distribution of airline distances between end offices of toll calls as presently established by customers. Connection results discussed in this paper describe the toll plant contribution to the transmission performance on built-up toll connections. In considering complete toll connections from subscriber 1001