Hunh? That doesn't make any sense at all.
You have a Cisco cable gateway used exclusively on Comcast Xfinity cable service. It is a cable modem containing a built-in router, WiFi access point, and an Analog Telephone Adapter function, and that ATA is used only to deliver Comcast Xfinity Voice telephone service. You can't magically connect an OBi IP phone without subscribing to a different Internet Telephone Service Provider (ITSP).
As for "there is no LED light on", what LED? There are a whole lot of LEDs on that phone.
