Hi.,

1 ) If you want to use “tel” link, then you can’t use the button shortcode. If you want to link the mobile number then kindly refer the below knowledgebase link,

Refer : http://wesupport.wpengine.com/knowledge-base/how-to-add-clickable-phone-numbers-in-wordpress/

2 ) You can also add the link like the below sample code,

[dt_sc_button link="url:http%3A%2F%2Fwedesignthemes.com|||"]