Guide to configure FusionPBX with ASTPP


I'm new in FusionPBX/Freeswitch and would like to integrate ASTPP for billing.
Does anyone had configured ASTPP as a gateway which could be the Trunk for FusionPBX?

ASTPP - Holds the VOIP Carriers and acts as a gateway Trunk (SIP/IP Auth/AIX2) and forward to the carrier to be log and billed.
FusionPBX - Act as a normal PBX (inbound and outbound would be routed over the SIP/IP/AIX2 if any for local trunking)

The design is attached below.

Kindly give me inputs and idea if this is doable.

Hi Sir,

Like your diagram I want implement the same design but not sure how secure this is though. We need assistance from this group to confirm if anyone has done this solution and if so what are the current concerns/issues...
IVOZ sounds promising...Still seems like it's in early development stages, but I'm downloading the ISO nevertheless. Daz, what about us post paid guys? Do you think it's best to run iVoz or ASTPP/FUSION? Seems like I can run all these services on the same box with IVOZ, is that correct?
I have paid ... and i'm disapointed ( multi-tenant) i use ASTPP only for SBC / Paiement gateway ... if not i have bug each days .. and fews option don'T work correctly ... but with SBC / Gateway paiement work very fine FusionPBX / FreePBX