This Recommendation describes the essential functions, procedures, and messages required for signalling between an International Switching Centre (ISC) and a digital interface to an ISDN satellite subnetwork. This signalling allows and appropriately equipped ISDN satellite subnetwork to perform on-demand bandwidth allocation for 64 kbit/s unrestricted and multirate ISDN calls, and protocol conversion for those calls which contain protocols that would otherwise experience throughput degradation due to the transmission delay of a satellite link. The framework of this signalling interface allows for growth for the potential inclusion of future ISDN network capabilities at the international interface.