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

SGCP
       Simple Gateway Control Protocol (MGCP)


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

Simple Gateway Control Protocol
SGCP

    (SGCP) An IETF work in progress,
   superseded by MGCP.

   (1999-04-26)