Recommendation: Check the Web Messenger Integration Editor document.
Reminder: To be able to customize the SMS provider the "Authentication" field should be set as "One-time password."
Any company can use their SMS provider if they prefer. For the customization process, we should make a request to their third-party tool. By using endpoint fields in the web messenger integration pop-up, we allow the customer to define the request.
This definition requires URL and HTTP method. The endpoint URL can be your own service or you can use a third party tool for that (HTTP method is set as POST by default.). If you prefer to use your company name as SMS label, you need to create an account on one of the provider that you choose. After then you will be able to use the provider endpoint, according to provider's documentation.
The header and the body fields can be used according to your service you will call. But the "Endpoint body" field should contain these two parameters:
1) Content: The SMS content message
2) Phone: The user phone number
After filling the related fields, click the "Save" button to save the changes you made :)