To overcome the problem of limited backhaul capacity and limited wireless channel capacity when downloading videos to smart phones, a method for transmission of data across a mobile telecommunications network, includes providing each Smartphone or other user station (Ua-Ud) with a memory cache (12) and a download app (10), and providing a server (2) in the core network with a server cache memory (16) and a download control app (14). Each user registers with the server, the server gathers information of internet web sites (URLn) accessed by the users from which downloads may be made, monitors the websites, and as and when updates appear on the websites, selectively downloads the updates in the server cache. There is then established a common data channel from the server, across base stations (3), to the users in order to download the updates to the user's memory cache (12).