Plain old user, not a vendor. Do not have anything to sell.
I was directed to sysmaster gateways as a way to receive calls via VOIp and play an IVR prompt to the caller.
But I decided to investigate more on the posibility of using a Asterisk, since at that point, the call did not go trought the billing yet, then the posibility of hackers or fraud is minimun.
Good luck Saul!!!