A common-channel signaling system defined by the CCITT in the 1988 Blue Book, in Recommendations Q. 771 through Q. 774. Note: SS7 is a prerequisite for implementation of an Integrated Services Digital Network (ISDN. ) ***PROPOSED ADDITION***A set of protocols that exchanges information between telecommunication systems and networks for establishing, maintaining, and terminating telephone calls within the PSTN. Note: SS7 is a prerequisite for implementation of an Integrated Services Digital Network (ISDN. ) Signaling System No. 7 is described in ITU-T Recommendations and ANSI American National Standards. This definition is being proposed for addition/change in the ATIS Telecom Glossary by the PRQC. If you have any objections to this acronym being added to the Telecom Glossary, please contact Paul Savitz, PRQC Committee Administrator, via email at psavitz@atis. Org to note your objection. ***