CCS7-English

Communication networks generally connect two subscriber terminating equipment units together via several line sections for message exchange (e.g. speech, data, text or images). Control information has to be transferred between the exchanges for call control and for the use of facilities. In analog communication networks, channel-associ- ated signaling systems have so far been used to carry the control information. Faultfree operation is guaranteed with the channel-associated signaling systems in analog communication networks, but the systems do not meet the requirements in digital, processor-controlled communication networks. Such networks offer a considerably larger scope of performance as compared with the analog communication networks, due, for instance, to a number of new services and facilities. The amount and variety of the information to be transferred is accordingly larger. The information can no longer be economically transported by the conventional channel-associated signaling systems. For this reason, a new, efficient signaling system is required in digital, processor- controlled communication networks.