my @data = (
      "Huber Karl      123",
      "Meier Hans      231", 
      "Gaukeley Gundel 666",
      "Schulze Maria   256", 
      "Klever Klaas    400",
      );

for my $i (0..4)
  {
  $data[$i] =~ s/([0-9][0-9][0-9])/Tel.: \1/;
  $data[$i] =~ s/([A-Za-z]+) ([A-Za-z]+)/\2 \1/;
  print $data[$i], "\n";
  }