Noname, what you say are true if you go with a hosted solution on their gateways and their rates, etc.
What I am saying is a “Hosted Billing” a hosted based billing engine for your gateways, which D-Tac is. The customer owns the gateway, the PSTN line charges etc. The customer also is in control of their own rates and routes they import to the database. Think of it as another way of leasing software with very little commitment. All charges are up front, monthly access fee, technical fee included unless something needs to be coded differently per the customers requests.
You find a 2,500 reliable billing system please tell me, I haven’t seen it. Get for what you pay for.