CAP V2 has been around for a long time. The Call Flow Use Case(s) is well established for Telephony between the
gsmSSF and the gsmSCF / SDF entities.
For your “converged” Charging Prepaid platform for Voice / Data I am assuming that CAP V3 (GPRS Data) and CAP V2 is integrated onto the same platform (gsmSCF / SCP / SDF). Next step is now to look at the Tariff Plan configuration and the “buckets” that have been configured for Voice, Voice-Roaming, Data, SMS, etc..
Mediated CDRs will also help to understand what has happened with the Voice session.
VBR/ Wallis Dudhnath