# weiter oben steht noch use Encode;
sub encode_7bit {
     my ($msg) = $_[0];
     my ($bits, $ud, $octet);

     foreach (split(//,$msg)) {
          my $b = encode("gsm0338", $_);
          $b = unpack('b7', $b);
          $bits .= $b;
     }
     while (defined($bits) && (length($bits)>0)) {
          $octet = substr($bits."0" x 7,0,8);
          $ud .= unpack("H2", pack("b8", substr($octet, 0, 8)));
          $bits = (length($bits)>8)?substr($bits,8):"";
     }
     return uc $ud;
}

&encode_7bit("Hällö wie gühtß?");
> C83D9BCD07DDD365D0D98FA67B7E

sub decode_7bit {
     my ($ud, $len) = @_;
     my ($msg,$bits);
     my $cnt=0;
     $ud = $ud || "";
     $len = $len || 0;
     $msg = "";
     my $byte = unpack('b8', pack('H2', substr($ud, 0, 2)));
     while (($cnt<length($ud)) && (length($msg)<$len)) {
          my $c = pack('b7', substr($byte,0,8));
          $msg.= $c;
          $byte = substr($byte,7,length($byte)-7);
          if ( (length( $byte ) < 7) ) {
               $cnt+=2;
               $byte = $byte.unpack('b8', pack('H2', substr($ud, $cnt, 2)));
          }
     }
return $msg;
}

# die Laenge 16 ist die Laenge des Strings durch 2
&decode_7bit("C83D9BCD07DDD365D0D98FA67B7E",16);
> H{ll| wie g~ht&â–²?