Angular 1.5 SharePoint, only show selected department - angularjs

Question

I have have made a small Angular employee phone book app from a SharePoint list. The app is based on among other tutorials:
http://ramdotnetdeveloper.blogspot.no/2016/05/sharepoint-2013-filtering-and-sorting.html
While the scope.sortExpression does its job sorting on lets say title, department, manager and so on....I would like since there are subdepartments be able to add those as options to the dropdown and only show those results.
So if i chose department DEP I 1, it will only show persons belonging to this department, DEP I 2 and so on is it possible through some sort of filtering?
var app = angular.module('ansattApp', ['angularUtils.directives.dirPagination']);
app.controller('ansattController', function ($scope, $http) {
$http({
method: 'GET',
url: _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getByTitle('Telefonkatalog')/items?$top=1000",
headers: { "Accept": "application/json;odata=verbose" }
}).success(function (data, status, headers, config) {
$scope.ansatte = data.d.results;
$scope.mySortFunction = function(ansatt) {
//Sorting Item
if (isNaN(ansatt[$scope.sortExpression]))
return ansatt[$scope.sortExpression];
return parseInt(ansatt[$scope.sortExpression]);
}
}).error(function (data, status, headers, config) {});
});
HTML
<div data-ng-app="ansattApp" class="row">
<div data-ng-controller="ansattController" class="span10">
<div class="form-group">
<div>
<h5>Sorter etter: </h5>
<select ng-model="sortExpression" class="form-control">
<option value="Title">Tittel</option>
<option value="Seksjon">Seksjon</option>
</select>
</div>
<input type=text" data-ng-model="search" placeholder="Søk etter ansatte,seksjon m.m." class="form-control"/>
<h1>{{search }}</h1>
<table class="table table-striped table-hover">
<tbody>
<tr>
<th>Etternavn</th>
<th>Fornavn</th>
<th>Tittel</th>
<th>Enhet</th>
<th>Kontor</th>
<th>Arbeid</th>
<th>Mobil</th>
</tr>
<tr dir-paginate="ansatt in ansatte | filter:search | orderBy:mySortFunction | itemsPerPage:25">
<td>{{ansatt.Etternavn}}</td>
<td>{{ansatt.Fornavn}}</td>
<td>{{ansatt.Title}}</td>
<td>{{ansatt.Seksjon}}</td>
<td>{{ansatt.Kontornummer}}</td>
<td>{{ansatt.Arbeid}}</td>
<td>{{ansatt.Mobil}}</td>
</tr>
</tbody>
</table>
<dir-pagination-controls
max-size="500"
direction-links="true"
boundary-links="true"
on-page-change="data.getData(newPageNumber)" >
</dir-pagination-controls>
</div>