How do I open WhatsApp on a new phone using my old number?
Access the official web page, download and install the application on your new phone, launch it and type your phone number in the provided field. Click OK and wait to receive the confirmation SMS. Once you receive the SMS, tap the provided link to verify your phone or paste the code in the WhatsApp field. After the confirmation process succeeds, you can use WhatsApp on your new phone. Check the I'm going to change my number and/or phone, what should I do? page for further information.