There is, however, a distinction between running ads that only use facts that make your product look good and making unsubstantiated claims. That is why AT&T has filed a formal complaint with the NAD against Comcast. Comcast offers mobile services under the Xfinity Mobile brand in collaboration with Verizon. It is only available to Comcast customers who have home internet service, and calls are routed through Comcast’s WiFi hotspots and routers when they are available.