I checked and sure enough, static & then the call drops and no voice mail offered. Note that the outgoing calls and dial tone are absolutely normal!
I thought it was an Ooma problem for sure. After a bunch of trouble shooting (restarts, checking cables, router restarts, isolating cables...) it turned out to be a corded GE phone causing the problem. The 3 AA batteries inside the phone had drained and corroded. It seems the off-gasses affected the boards because the system now works normal with just that one phone removed!
I wanted to pass that on in case someone ever has that same symptom on their Ooma.