This Recommendation provides a reference architecture for existing maritime and aeronautical systems and also provides high-level reference connections for maritime and aeronautical call/connection set-up. The primary purpose of the reference connections for maritime and aeronautical systems is to provide a basis for developing related-traffic Grade of Service (GOS) Recommendations. The underlying call flow model in the reference connections should be used as a basis for more implementation-specific configurations for detailed performance analysis and GOS target setting. This Recommendation is initially focused on satellite based systems and circuit-switched user plane traffic.