I installed a new telo a couple weeks ago and when I received my first call I couldn’t hear the caller’s voice. They could hear me. I called Ooma support and they told me that there are many incompatible wireless phones that will not work with Ooma. They suggested that I try using a wired phone for troubleshooting but I’m am many miles away from the Ooma. I am using the Panasonic KX-TG885 DECT 6.0 Bluetooth 5-Handset Phone Bundle from Costco.
Anyway to make a long story short, I am on Frontier FIOS, so I added the Ooma to the DMZ and configured the router to enable SIP bypass, and now it all works fine. I don’t know which of the 2 settings fixed it or if both were needed.
I hope this helps others experiencing this problem. Ooma support never suggested looking at these option. The SIP setting will vary by router type.