Abstract: A handset capability proxy server (1) automatically determines data concerning capabilities of mobile devices and links to users as the devices are used. Event handlers/filters (25, 26) listen to signalling and messaging traffic at different locations in a network. The filter (25, 26) filters out data not relevant to device capability. The handler accesses a RAM cache (37) to dynamically determine if there has been a capability change for a mobile device identifier. It transmits changes to a kernel (10) via a message bus (12). The kernel (10) manages a persistent database (41, 44) of consumer data and device capability data, and automatically notifies subscribed applications in real time.