Common control features for the step-by-step system

The arrangement of Bell System step-by-step (SXS) offices to provide Touch-Tone calling and common control features, either individually or in combination, is described. If either feature is provided first, the other can be added conveniently at a later date. Advantages of translation, code conversion, alternate routing, and multifrequency outpulsing in step-by-step offices are described; the central office equipment which is required in order to provide the Touch-Tone calling and common control features will also be mentioned.