So it took me a couple of days of testing and changing settings to finally get my alarm system to work with the Primus VoIP. All the help that I had from their tech support was that the fax transmission speed has to be no higher than 9600bps, that's what their limited by. I couldn't find anyway of making my alarm panel communicate slower, cause I assumed that it was transmitting too fast since I kept sending the information over and over on each call but it would never get through!
I finally got a breakthrough, when I realized that the alarm panel communicate slower when using the SIA format rather than the Contact ID. Lo and behold, it worked! It communicates perfectly using the SIA format, and I've even set the line seizure! Just thought I'd add this here for the others when you guys are searching regarding the same problem, lol!
Oh and of course, I've got my fax transmitting as well now, tested it out the other night, works like a breeze!