Telephone field to make calls

Good Morning,
I am trying to create a link so that I can make calls from a phone field in a table.
I'm using an html <a> tag in the columns: data, but it doesn't show me the field data.

{
   "render": function (data, type, JsonResultRow, meta) {
      return '<a href="tel:'+JsonResultRow.tb_contacto.telefonoFijo+'"></a>';
   }
},

Thank you