How to Validate a Phone Number in AngularJS

<!doctype html>
<html>
<head>
<title>angularjs Validation of a phone Number</title>
<script src="http://code.angularjs.org/1.2.9/angular.min.js"></script>
<style>
.error {
color: red;
}
</style>
<script>
var app = angular.module('myApp', []);
app.controller('mainCtrl', function ($scope) {
$scope.phoneNumbr = /^\+?\d{2}[- ]?\d{3}[- ]?\d{5}$/;
});
</script>
</head>
<body ng-app="myApp">
<ng-form name="myForm" ng-controller="mainCtrl">
<div><b>Enter your Phone No. in the format of (91-xxx-xxxxx) :</b></div>
<div><b>Example of a valid Phone no is :91-999-99999</b></div>
<div>
<input type="text" placeholder="+91-xxx-xxxxx" name="phone" ng-pattern="phoneNumbr" ng-model="phone" />
<br><span class="error" ng-show="myForm.phone.$error.pattern">Please Enter the Phone no matching pattern [+91-xxx-xxxxx || 91-xxx-xxxxx]</span>
</div>
</ng-form>
</body>
</html>