Hi, I want to use an ampersand in a button: A&R How can this be done?

Hey, I saw this topic: https://answers.themler.com/questions/2302/please-add-an-option-to-add-an-icon-or-image-to-buttons In this topic they are talking about an icon in a button. But I can't find...

Hello, I want to create a 'click to call' button. If you click on it you'll call the number. Like this <a href>0 000 000 0000</a> How can I insert HTML into a Button in Themler?