Hi,
If I'm understanding correctly you want to set up your machine as a Voice mail Box.. (I'm not clear if you want that or dial-in access to a terminal or both)
Luckily the answer to both is related .. you need to set up a modem aware "getty" so probably mgetty and/or vgetty. From my limited experience with these (mgetty) they are fairly easy to set up.. there are also many helpful howto's just google
+mgetty +"voice mail" +howto
and you should find some helpful ones or you can start here:
http://linuxindia.virtualave.net/lamhowto.html
It describes some of the steps needed to set up a voice mail system (tho not specifically on Suse) but it should get you headed in the right direction.
Hope this Helps
Freemor