Sippy B2BUA is a RFC3261-compliant SIP Back-to-back user agent (B2BUA).
Unlike a SIP proxy server, which only maintains transaction state, the B2BUA maintains complete call state and participates in all call requests. For this reason it can perform number of functions that are not possible to implement using SIP proxy, such as for example accurate call accounting, pre-paid rating and billing, fail over call routing etc. Unlike PBX-type solutions such as Asterisk for example, the B2BUA doesn't perform any media relaying or processing, therefore it doesn't introduce any additional packet loss, delay or jitter into the media path.
Sippy B2BUA supports RADIUS AAA protocol, which is compatible with Cisco VoIP gateways allowing it to be seamlessly integrated into existing networks.