Please uninstall and reinstall the app.
iOS:
To uninstall: Settings > Apps > Select 3Connect > Uninstall
To reinstall: go to Apple Store > search for 3Connect softphone > install > once installed insert your username and password.
Android:
To uninstall: Settings > Apps > Select 3Connect app > Uninstall
To reinstall:   Visit your app store > search for “3Connect softphone” > install > once installed insert your username and password.
To get your username and password please go to the 3Connect portal (you’ll have received your username and password from Three) and go to “devices”, locate your app, click the edit icon to see your app username and password. Please don’t copy and paste these. Instead, type in both your username and password. Remember to avoid leaving spaces before and after.