V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

SS7
       Signaling System 7 (ISDN)


The Free On-line Dictionary of Computing (30 December 2018):

Signalling System 7
SS7

    (SS7) A protocol suite used for communication
   with, and control of, telephone central office switches and
   their attached processors.

   (1995-03-01)