You can only send a text message up until 24 hours after receiving a message from the user. If you have not received a message from the user within this time, you will need to start a new conversation by sending a Template message.
Specify text in the type field. A text message can be a maximum of 4096 characters long.
Send a text message
Formatting in Text Messages
WhatsApp allows some formatting in messages. To format all or part of a message, use these formatting symbols:
Your total is *$10.50*.
Welcome to _WhatsApp_!
This is ~better~ best!
Three backticks (```)
```print 'Hello World';```
Sending URLs in Text Messages
By default, the mobile WhatsApp application recognizes URLs and makes them clickable. To include a URL preview, include "preview_url": true in the message body and make sure the URL begins with http:// or https://. A hostname is required, IP addresses are not matched.
"body": "You have to check out this amazing messaging service https://www.whatsapp.com/"
The majority of the time when you send a URL, whether with a preview or not, the receiver of the message will see a URL that they can click on.
URL previews are only rendered after one of the following has happened:
The business has sent a message template to the user.
The user initiates a conversation with a "click to chat" link.
The user adds the business phone number to their address book and initiates a conversation.
If the end user did not initiate the conversation with you - you must use a Template message instead.