Variable data for HTML pages is transmitted using the messaging service of a mobile telephone network (4). At clients (13, 16), data in received messages is merged into HTML page templates to create pages from display using a web browser program. The messages are transmitted by a server (1) and cached in the clients (13, 16). When a URL is generated by the web browser program, it is analysed in the client (13, 16) and, if a response is need from the server (1) or information needs be recorded at the server (1) or sent to another location, a message service message bearing URL data is transmitted from the client (13, 16). The server (1) processes these messages and takes the appropriate actions in response. The system can be used to provide passive information dissemination and interactive services such as flight booking or multi-player games.