We did call flow test, one call flow translation route from customer IVR to CVP fails all the time, as calls are dropped on ingress voice gateway in one second. Telco provider blamed voice gateway not sending 'alert' or 'call progress' back by certain timer, so drop the call. After checking log/debug, CVP never sends out any 'alert' or 'progress' signal back to gateway. And we tried to find if we could force alert signal back from gateway, no luck so far. IOS does have a few commands for H323, we use SIP.
Is it possible to let CVP issue call progress signal? Or force this from IOS?
Gateway: AS5400 IOS 12.4.15T
Telco switch: DMS100