Ok, I figure it out.
In class.pdf.php i insert
$this->Cell(30, 17, 'Phone:', 0, 0, 'R', true);
$this->SetFont('Arial', 'B', 11);
$dept = $ticket->getDept();
$this->Cell(3, 17, $dept?$dept->getPhone():' -- ', 0, 0, 'L', true);
I defined getPhone and i use that field from ticket view.