Implementing VoIP Support in a VSAT Network Based on SoftSwitch Integration
Satellite communications based on geo synchronous satellites are characterized by a large delay, and high cost of resources. VoIP applications over satellite networks must thus be handled very carefully so as to provide quality of service, as expected from voice calls, namely: secure resources for a call throughout its duration, regardless of other calls and other data traffic being present in the system. Furthermore, jitter and delay must be kept to a minimum while maintaining as high satellite resource exploitation efficient. These subjects are well treated in the previous generation of satellite telephony products (Also referred to as "Native telephony" Basically, the circuit switching approach dominated these solutions, with specific solutions applied to both the access level and the application level. The media itself, derived from the requirement of bandwidth efficiency, used the very same CODECs used for VoIP such as G.723 and G.729. The native telephony solution is jitter free, minimal delay, total QoS (regardless of other calls or data) and extremely efficient. The purpose of the current work was to capitalize on the existing infrastructure and its benefits and to port them to the VoIP environment. The approach described herein was implemented in Gilat's SkyEdgeTM product and is operational for about 2 years. Introduction Satellite communications based on Geosynchronous satellites are characterized by the following: High delay caused by the propagation path of the information from earth to the satellite and back (about 250[ms] and 500[ms] round trip)