This is what I did: 1. Set your user agent to an S40 device of your choice. 2. Go to WhatsApp site and download the .jad file. 3. Open .jad file to find the url of the .jar file and download that 4. Extract opt/whatsup/bin/whatsup 5. In you favourite hex editor search for old API version number e.g. 2.4.12 and replace with new one. 6. Save binary and copy over the existing one.