had the same problem witth XP 2002 SP1, Motorola SM56 PCI
voice/data/fax modem that worked perfectly under W98FE. Here is my
solution
downloaded the driver from the website
www.motorola.com/softmodem/driver.htm#universal
this page lists all available motorola drivers and i had to try out
several before i found the one that worked. that one was
WXP/2K DFV universal 6.02.13
Then based on another poster's suggestion i changed the COM setting
from COM1 to Com4 in WinXP. this was via the menu choices as follows:
CONTROL PANEL>>SYSTEM>>DEVICE MANAGER>>MODEMS
(the modem icon should have a yellow alert sign on it).
i right clicked on Motorola SM56 Speakerphone Modem and chose
PROPERTIES followed by teh tab ADVANCED followed by the button
ADVANCED PORT SETTINGS. then against COM PORT NUMBER (bottom left) i
chose COM4 (COM2 and COM3 were listed as being in use). strangely
enough WinXp now has changed this to COm3. But the modem does work as
evidenced by this post.
i'm guessing both of the above cleared my problem and i hope this will
prove helpful to you too.
Cheers
Darryl