A context is an association between a number of terminations. The context describes the topology (who hears/sees whom) and the media mixing and/or switching parameters if more than two terminations are involved in the association.
ITU-T H.248.38 SPANISH-2006 Referenced Document
ITU-T H.248.1-2005 Gateway Control Protocol: Version 3 Study Group 16 Audiovisual Services Systems and Multimedia System Infrastructure - Communications Procedures Study Group 16