Abstract: A server system receives, from a first user device through a first network carrier, a request to access content. One or more characteristics of the first network carrier are determined from the request, including at least one of an identity of the first network carrier and a network type of the first network carrier. The determining includes performing a look-up using information from the request. Furthermore, the server system performs at least one of: (1) storing the determined one or more characteristics in association with the first user device in a first data structure, where the first data structure specifies, for multiple user devices, at least an identity of associated network carriers and a network type; and (2) providing access to requested content, which includes content customized based on the determined one or more characteristics.