The quintum run the best with a external IVR server. That is just a old P.C, with the audio files on it and a TFTP client software on it.
The IVR could be colocated with the gateway or across the internet if you have enough bandwith.
Anyway, the quintum only “download” audio from the server once, keepeing that file on the memory after the first use.
After few hours of operation, the TFTP transfer is only a trickle, only for the files that the gateway did not use until that point.
The files for the IVR (audio) are on the quintum website (you will need a logon)
I do have the ones in spanish somewhere, but it should be easy to get them from quintum.
You could have the TFTP server on the same chassis than the billing as long as you have enough hard drive, memory,etc.