To make sure that the router isn't blocking any ports, reserve a static IP address in your router for the Ooma device. Next place the Ooma device's IP address in your router's DMZ. Reboot router, than reboot Ooma device.
Something else to try:
a. Access your Ooma Telo “home port” by temporaily plugging in a network cable from the Ooma Telo’s “Home” port to a computer’s network card port. Sometimes you have to restart your computer after installing the network cable, so that a proper connection occurs.
b. Type http://setup.ooma.com or http://172.27.35.1 in you browser address window and hit enter. The “Ooma Setup” window opens.
c. In the left hand Navigation window, select “Network”.
d. Under “Modem Port MAC Address”, select Use Built in:
e. Select the “Update button”.
f. Do a “cold boot” of the modem.
g. Do a “cold boot” of the Router.
h. After the router cold boot, do a “cold boot” of the Ooma device.