Power down your modem. If it has a backup battery, disconnect the battery.
Power down the Ooma Telo. Disconnect all cables from the Telo
Connect a LAN cable between the LAN jack on the modem and the “To Internet” jack on the Telo. Do not connect anything to the “Home” jack.
Connect a telephone to the phone jack on the Telo. Do not connect to your house wiring.
Power on the modem and wait until it has completed synchronization with your ISP.
Power on the Telo and wait until the Ooma symbol is blue. If there is an outstanding firmware update waiting for the Telo this could take up to an hour and at least one reboot would happen. Do not try to help it. Leave it untouched until it is online.
Once the Telo is online pick up the phone and check for the Telo musical dial tone.