diff --git a/app/Http/Controllers/AuthController.php b/app/Http/Controllers/AuthController.php
index 2736a87..235287c 100644
--- a/app/Http/Controllers/AuthController.php
+++ b/app/Http/Controllers/AuthController.php
@@ -8,6 +8,8 @@ use App\Models\User;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Auth;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Session;
 
 class AuthController extends Controller
 {
@@ -15,7 +17,28 @@ class AuthController extends Controller
 
     public function login(LoginRequest $request): JsonResponse
     {
-        if ($this->attemptLogin($request))
+        $inputTelephoneId = $request->input('telephone_id');
+
+        $user = User::where('username', $request->username)->first();
+
+        if ($user->is_online && !empty($user->telephone_id)) {
+            return $this->errorResponse(__('messages.user_already_online'), 409); // 409 Conflict
+
+        }
+        if (!empty($inputTelephoneId)) {
+            $previousUserOnThisSystem = User::where('telephone_id', $inputTelephoneId)
+                ->where('is_online', false)
+                ->first();
+
+            if ($previousUserOnThisSystem) {
+                DB::table('sessions')
+                    ->where('user_id', $previousUserOnThisSystem->id)
+                    ->delete();
+            }
+        }
+
+
+            if ($this->attemptLogin($request))
         {
             $request->session()->regenerate();
             $this->updateUserInfo($request);
@@ -35,9 +58,13 @@ class AuthController extends Controller
         Auth::user()->update([
             'last_login' => now(),
             'telephone_id' => $request->telephone_id,
+            'is_online' => true
         ]);
+        DB::table('sessions')
+            ->where('user_id', Auth::id())
+            ->where('id', '!=', Session::getId())
+            ->delete();
     }
-
     public function logout(Request $request): JsonResponse
     {
         Auth::user()->update([