Can I add a button for customers to text us on my webpage?
Work with your web developer to create a button on your website that directs your customers to a URL. Use the URL "sms://+" followed by your Zendesk Talk phone number with no dashes or spaces. For example: "sms://+13456789876".
You can find your account's Talk phone number in Zendesk Support under Admin gear > Channels > Talk > Numbers.
To make sure Text is enabled for your Talk number, visit this article: How do I add Text to my Talk number?