If you use an older version of Chat app on your phone, it will be discontinued after 10th of Oct. 2014. To keep chatting with friends, you need to get a new app.
If you use Facebook or GTalk, please download Nimbuzz from Nokia Store.
If you use Yahoo! Messenger, you can access this service via the following web link: http://m.yahoo.com/w/bp-messenger
If you use Nokia Chat powered by Yahoo!, please visit the store and determine if your device is supported by the app Chat by Nokia.
If your device is not supported by Chat by Nokia, you can access these services via the web: Nokia Chat powered by Yahoo! http://m.yahoo.com/w/bp-messenger/