Where in the US is the Radius Server? How many minutes per month are you averaging?
Depending on where the server is in the us, the multiple hops can affect the post delay in authentication via Radius. Best to have a server located near the equipment, but if that is not feasible maybe somewhere else in the region. Are you communicating with cisco’s here in the us also or quintum networks?
One thing that will help on bandwidth costs is partnering or deplying Quintum hardware, put their Call Relay box in Cambodia which the Cisco places a call to the call relay then through Quintum’s PacketSaver option communicate to other Quintum hardware (US in this example) also using PacketSaver and your bandwidth saving can be as high as 52%. Satellite is not cheap as we know.
I have a radius server in Los Angeles for prepaid and postpaid traffic if you would like to setup some test calls let me know. We set up your own dedicated SQL Database and Radius server