Ng-href="tel: redirecting to call with empty number

[mhartington]

You should take a look at this article

Avoid Angular.js from adding "unsafe" tag in ng-href

Basically you have to tell angular in your config set up that it should allow tel

app.config(['$compileProvider', function($compileProvider) {
  $compileProvider.aHrefSanitizationWhitelist(/^\s*(https?|file|tel):/);
}]);