Voipfuture Qrystal uses a powerful two-stage correlation mechanism to correlate all media and control plane data measured at different points in the network.
Qrystal Probes first apply a patented online correlation mechanism, which correlates signaling and media information while VoIP sessions and media streams are still in progress. The correlation mechanism is able to identify and track media streams in all phases of a session, including early media (ringtones, pre-call announcements) from multiple parties. Additionally, Qrystal recognizes media streams that have been modified on the IP layer to pass through firewalls and Network Address Translators (NAT). This correlation step also allows to associate xDR and RTP stream data with matching trunk and numbering plan definitions. This is subsequently used to create statistics and KPIs.
In the second stage, Qrystal correlates all xDRs and RTP stream data of a call measured at different points in the network to create call detail records (CDR) representing an end-to-end call view. All RTP streams and xDRs of the same call receive a CDR tag, so all of them are linked to their CDR.