kbp's

I have one phone line and a dial-up modem.  Recently, when I have connected to my server, the connection message indicates 33.6 kbp's where previously the number shown was 52 - 54 kbp's.  My server indicated that I could download free modem software to improve my speed.  But, I haven't a clue as to what to look for.  Any help would be greatly appreciated.