Win32::SerialPort is OO and not that bad to use. Have a look at the examples here. Of course you could always just write the required XS wrapper for the TAPI32.DLL. Win32::Internet is the wrapper for the WININET.DLL and should work as a template for what you need (it is part of libwin).

If you don't like writing XS, you might be able to get away with writing some wrappers with Win32::API module. It works like this:

      use Win32::API;
      my $function = Win32::API->new(
          'mydll, 'int sum_integers(int a, int b)',
      );
      my $return = $function->Call(3, 2);

      # or, if you don't like the ->Call() syntax:
      Win32::API->Import(
          'mydll', 'int sum_integers(int a, int b)',
      );
      $return = sum_integers(3, 2);

      # Works great for system DLLs, too:
      Win32::API->Import("kernel32", "int GetCurrentProcessId()");
      my $PID = GetCurrentProcessId();
[download]

There's even support for defining structures within your perl script, for use with the DLL's interface.

If you only have a handful of functions to call, this may be the way to go for you. Assuming, of course, that you have access to the documentation for that particular DLL...

:)