public function update(Request $request, $id)
 {
     $phone = phone::find($id);
     $validator = Validator::make($request->all(), ['number' => 'required|min:9|max:10|unique:phones,number,' . $phone->id, 'description' => 'required|min:3|max:50']);
     if ($validator->fails()) {
         return redirect()->route('phone.edit', ['id' => $phone->id])->withErrors($validator)->withInput();
     }
     $phone->fill($request->all())->save();
     $initial = strtoupper(substr($phone->contact->nickname, 0, 1));
     return redirect()->route('agenda.initial', ['initial' => $initial]);
 }