A server receives, from a first mobile device, a request for content identified by a first resource identifier and a set of presence codes. The set of presence codes includes a presence code for the first mobile device and at least one other presence code for one or more mobile devices in proximity to the first mobile device. The server selects a set of allocated resource identifiers associated with one or more presence codes for one or more of the mobile devices in proximity to the first mobile device having the content cached therein. Each allocated resource identifier in the set is different than the first resource identifier. The server then sends to the first mobile device the set of allocated resource identifiers and associated presence codes for use in retrieving the content cached in at least one of the mobile devices in proximity to the first mobile device.