3rd party billing system - how to Export Via CSV or collect via API

is it possible to use a 3rd party billing system that can get data by:
Pulling CSV or txt files from a FTP server (
API getting the info out (preferred option)
Or posting a CSV via API (least preferred)
(the billing system is Datagate - because we deal with VoIP calls and Syncro cannot pull and rate calls out of upstream provider systems, we need to get Syncro billing data out of syncro)

You could create the invoices in Syncro and then can query invoices via the API which is probably going to be your best route