That's fine. Sometimes one p2p app is more suited to one person's setup than another due to different set ups. Your Voyager modem is by BinaTone. Some of their modems use NAT which limits incoming access thru most ports. At present I can't find anything on the Voyager 100 but I'll do some more searching.

Other people have had problems with your model of modem; see here: http://www.reviewcentre.com/reviews6179.html & also HERE (hardware issue)