Least helpful..
this was their message:
Because this what they replied.
Hi,
Thanks for your message.
You can place a free voice or video call with any contact in your phone’s address book that also has a WhatsApp account. Voice and video calling uses your phone’s internet connection instead of your mobile plan’s minutes. Internet data charges may apply.
Voice calling OS requirements:
Android phone running OS 4.0.3 or newer
iPhone running iOS 9 or newer
Video calling OS requirements:
Android phone running OS 4.1 or newer
iPhone running iOS 9 or newer
Note:
In order for voice and video calling to also be available, make sure you update WhatsApp to the latest version available on your phone's app store.
Make sure you have a strong cellular connection or Wi-Fi network when placing or receiving voice or video calls.
You can’t access emergency service numbers through WhatsApp such as 911 in the United States. To make emergency calls, you must make alternative communication arrangements.
If you have any other questions or concerns, please feel free to contact us. We'll be happy to help!