See New Features Rolling Out Soon
You can add a button on your site to take people to another URL or page.
On a computer, open a site in new Google Sites.
On the right, click Insert > Button.
Enter a name. This will appear on the button.
Paste a URL the button should point to, or choose a page on your site.
Click Insert
Buttons now have three styling options: filled, outlined, and text. By default, a newly added button will be filled, but you can can change the button’s style using the dropdown in its toolbar.
Create a sms link at https://zwt.co/sms/
Copy the link
Insert a button and configure it to the link from step 2