VirtualBox serial port, limit of two?

Question

Using VirtualBox, Is there a limit of two serial ports per VM? I'm currently engaging in a task that requires more than two, but less than or equal to four ports. I'm at a loss of what to do to get COM3 and COM4 up? How do I do it if the Virtual Box GUI doesn't currently support more than two serial host devices? Can I configure them external to the GUI? Is there a hard-cap on two devices? And, if so, for the love of god, please entertain me with the reasoning? I know Windows and Linux don't impose such a limit, it would seem awkward to impose it in virtualization layer.

This is for cheap dial-in project with proprietary Windows tools. I'm using a Quatech serial multiport adapter to provide the ports to multimodems.

Answer 1

From the Serial Ports section of the Virtual Box Manual:

...you can configure up to two virtual serial ports simultaneously.

vboxmanage modifyvm --uart will let you configure these 2 virtual ports but not add an additional port.

Answer 2

I'm not 100% sure this will work, but it appears as if there is a utility VBoxManage which has the ability in modifyvm mode to add serial ports beyond the ability of the GUI.