Sameer,
Late to the questions. Sandeep is correct, but let me make it simpler. First, you did not need a four-line fax board. That would be for an office that is receiving and sending tons of faxes daily. You could have easily gotten away with a one or two port board, in fact, that is all you can use right now.
Look at it this way. Use all of your other lines for what they were before. Digital phone lines. You have one dedicated fax line. It has to go in one analog port on your fax card. Period. It will be used for sending out and sending in. You will likely not have issues with faxes blocking each other as these are very smart cards. As long as you have them set up to do multiple tries.
If you have two lines (with two separate fax lines), you can set it up with one in, one out or one line for in and out and one for incoming.
What scares me is that you only have one dedicated fax line. So what do you use for your walk-up fax? Do you expect every one in your office to do all faxing through the fax server. I would guess you would have a mutiny. For instance I just printed ten pages for ten scripts (has to be that way) and couldn't ePrescribe. I asked my staff to fax them. They are not going to scan them in and then fax them. So you would need another line for that fax.
