If you changed your phone number and kept your same BlackBerry, you can change your number within WhatsApp. Before proceeding, make sure that your current number is activated on your phone and that you can receive SMS messages and phone calls.
Using the Change Number feature in WhatsApp will:
If you use our Change Number feature, your chat history will continue to be available on your phone with the new phone number as long as you continue using the same phone.
Please make sure your WhatsApp contacts have your new phone number saved in their phone’s address books to ensure a seamless messaging experience.
Please follow these steps to change your account phone number:
WhatsApp Support Team