You can use the image block with a photo or icon and size it using spacers, 

 
phone-icon-md.png

Say something about a call here...

 

...or You can use a Code Block with special CSS to give your text a special appearance...

This is an example of a way to put a colored (in this case light grey) box around text using a Code block and could be used to highlight your special text with an inviation to call...

...Or maybe some different colors

This is an example of a way to put a colored (yellow in this case) background behind colored (in this case green) text using a Code block and could be used to highlight your special text with an inviation to call...