If you become banned, you will receive the following message from within WhatsApp:
"Your phone number is banned from using WhatsApp. Contact support for help."
Be aware that we ban accounts if we believe the account activity is in violation of our Terms of Service.
Please review the “Acceptable Use of Our Services” section of our Terms of Service carefully to learn more about the appropriate uses of WhatsApp and the activities that violate our Terms of Service.
We may not issue a warning before banning your account. If you think your account was banned by mistake, please email us and we will look into your case.
72 hours after your account has been banned, your friends will no longer be able to see you in their Favorites list (Contacts tab on Android).
If you see the message "You’re temporarily banned from WhatsApp", please read this article.
WhatsApp Support Team