We want to proxy our SIP connections (not media) to our providers for 2 reasons. PrePay billing and direct media. Is CGRateS + Kamailio good for that? My 2 main concerns are fraud and call quality I am not opposed to using Freeswitch if running it with bypass-media=true will accomplish the same thing without introducing any potential complications. User/pass is not an option either. Our providers only do IP authentication and we also only want to do IP authentication on our end.
We don't want the media going halfway around the world and affecting call quality and we don't want to deal with anything related to codecs and we do not need to listen in for any reason. We understand that end users will be able to see our Carrier IP with direct media and possibly the SIP header (record route) if we can't strip that out. We can live with that but not any sort of fraud that takes money out of our pocket.