WhatsApp uses the same internet connection as web browsing and email on your phone. If you use WhatsApp while your phone is roaming, data charges might apply. Contact your mobile provider for more information about roaming in other countries.

If you don’t have an international data plan, we recommend you turn off:

• Mobile data and data roaming to avoid data roaming charges. You can visit your mobile provider’s support website for instructions.
• Media auto-download over your cellular connection and roaming to avoid extra data charges.

Related resources:

How to configure auto-download on: Android | iPhone