Please install WhatsApp if you have not done so from the official site. if you haven't done it yet
WhatsApp quickly and easily recognizes which of your contacts are using WhatsApp by accessing your phone's address book.
The first method using the address book phone numbers
- Save a contact's name and phone number in your phone's address book.
- Save the number in full international format +66 94 635 76 37 like "HGH Thailand"
- Open WhatsApp and go to the Chats tab.
- Tap the new chat icon > Refresh.
- Find "HGH Thailand in new chat and start chat with us!
The following method is easier - by clicking on the link
Click on the link from your phone (if you have installed WhatsApp, the window will open automatically.