A network device and method are directed towards determining whether a carrier gateway is likely to be associated with a mobile carrier service. Content/service providers receive request for content along with a network address of a gateway device providing the request. If the network address is unknown, the content/service provider may be provided to a new gateway identifier that is configured to determine a likelihood that the gateway device is configured to provide services to mobile devices. Based, in part, on the determined likelihood, a gateway device's capability may also be determined, such that the content/service provider may then select to provide a response, degrade a response, or reject a request for the content, service, or the like.