Auto Detection for calling number: Before each call has been sent out, our system will check the number you dial and give you alert if we find the number doesn't seem to be a valid number according to your auto prefix setting and give you options to continue calling or cancel it to change. If you have any questions about using our app, you can open our app, then go to "Settings"->"Contact Us" to send one message to us. Our support will help you in the first place. Thanks.