Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: Does this support 2 phone lines with one cable?  i.e., 4 pins inside the opening, not just 2.  Thx.
Document: You can switch the phone line from the one to the other, then clicking on the appropriate dialup icon on your Desktop. Nice having a backup, already installed and configured.Maybe it has something to do with running Windows Xp, I can't be sure, but I distinctly recall many years ago with both a Win98se setup as well as a Macintosh OS8.5 machine that 2 PCI card modems plugged in at the same time WILL NOT WORK!!
I apologize to Amazon for not purchasing this from them but one of their competitors had free shipping at the time I ordered 2 weeks ago (N_____)  so I bought it there, but I'll include a post here because most of my purchases are at Amazon and Amazon receives so many visitors. On with the discussion....The modem, the Rosewill RNX-56USB, it's great.
Actually, I copied this directory off the CD to my hard drive, and backed this up on 2 flash memory drives so I never have to go near this Rosewill CD-ROM again. I'm gonna burn this sucker tomorrow. Following the Add New Hardware approach, INSTALLATION WAS A SNAP. Easier than brewing morning coffee.One other goofy thing about this product.
I'm completely happy with this tiny fax machine that can simply hang off of one USB port. It works flawlessly in Windows 7. One star off because it doesn't provide pass-through connectivity for your phone, though; you have to use a Y-adapter with your phone line coming from the wall.
This was surprisingly easy to use. I plugged it into my USB port, connected my phone line to it, opened windows fax and scan, clicked one or two intuitive menus and I got my faxes. I haven't used it to send a fax, but it seems just as easy as long as you have the capability of scanning what it is that needs faxing.
Excellent product,fast tech support,fast shipping. Regards
Oops, my motherboard didn't support wake on USB, so switched to an internal U.S. Robotics that works fine. (First USR was defective, though.)
Easy to install and does whats excepted of it I use it on 2 of my pc.s using windows xp and windows 7
Great service in delivery. Documentation did not indicate compatibility with Win7 or Win8, but reviews did. Win 7 found and installed driver, but Win8 did not - it recognized connection but did not try to find (or ask for) driver. But when I tried to connect to telephone line,l everything worked as desired. Documentation should support these systems to reassure purchasers! I am happy with product, but not with documentation.
I need to fax in forms for medical reimbursements. I got a new pc that does not have many slots for internal boards. I didn't even know things had gotten this simple. Really nice to be able to just plug into a usb port!UPDATE 3/2/14 going on 6 months still works fine on my win7 home premium 64 bit desktop pc.
Answer: I do that, works fine I just plug in a splitter and this will work with the type you have. and yes I have a 2 line system hard wire. I just split so I can use the phone line too