A method of broadcasting a file to terminals in a wireless network, such as a mobile radio network. The file is divided into a set of blocks which are to be transmitted to the terminals. An interval for response by the terminals is calculated depending on the number of active terminals which require the blocks. Messages containing the blocks and the response interval are then broadcast over the network. Responses indicating missing or imperfect blocks are received from the terminals. These steps are repeated until all of the terminals have received a complete set of blocks or have become inactive. Shorter response intervals are calculated as the number of active terminals is reduced.