use Tk::Event qw(DONT_WAIT);

sub push_button { 
       $txt -> insert ('end',"Dialing $number\n");
     
      #$modem->dial($number);
        my (@n) = $number =~ /\d/g;
        
        foreach my $d (@n){
           
         $modem->atsend(  'ATDT'. $d . Device::Modem::CR );
           DoOneEvent(DONT_WAIT);    
        }

}