after trying multiple routing scenarios...(all actually worked) I discovered that if dialing slower at IVR prompt the call would complete to any target, ie misc destination, ext on iax trunk to remote system , etc...
for some reason slow and deliberate key presses works every time and even moderately faster the call will fail saying "we did not receive a valid response"...
Any suggestions on how to address this would be greatly appreciated (DTMF recognition sensitivity?)
I had outgoing callers tell me they had some trouble dialing other auto attendants and digits being recognized and when they dialed slower it worked.