What you can do is add your desired content or html code as an announcement content.
1. Go to Dahsboard>>Appearance>>Customize>>Header Top bar
2. Add your desired content/ html code(for instance: +19812345600) inside Small Announcemnet Content
3. Make sure you haven’t hidden top bar or announcement area inside the field Top bar Display. However you can hide the social icons if you don’t want to display by checking hide social icons inside Top Bar Display.
4. Save changes and you’re done.
Let us know if you meant to enquire us about anything else.