HOW TO SET THE TELEPHONE IN WEBSITE SETTINGS:

Under the Website settings you can easily add the your contact details or company contact details. First click on the gear icon and then click on Website Settings. Finally, type in your telephone details in the left column.

Here is how to set the telephone in website settings:

Step 1: Click on the gear icon.  (in orange) (See website settings.)

Step 2: Click on website settings (A).

Step 3: Under the General Settings tab the left column is for company details. Add the information about your phone number (in red).

Step 4: Click done

Adding a phone number is useful for clients to contact you. When you add a phone number, search engines can find it as part of your contact details and display it to your clients. 
When you add a phone number, this enables the 'Call Icon' for the mobile site. This allows clients/visitors to call you when they are on your site.