I have an Aztech Labs Sound III 336SP modem in a P200mmx win95, 32mb Packard-Bell. I also have call-waiting. I sometimes need to be able to get knocked offline in order to receive incoming phone calls (I work on a on-call basis). In the additional command strings box under modem properties, I have added the string 'S10=1'. I have also unchecked 'Use Error Control." It seems that occassionally I will get knocked offline by incoming calls (which is what I want it to do), but more often than not, the person trying to reach me hears ring after ring on their end, but it doesn't disconnect my modem and ring through to my phone. I do notice, however, that my connection has degraded significantly after someone has tried to unsuccessfully reach me by phone.
Are there any other steps I can take to increase the probability that an incoming phone call will disconnect my modem and ring to my phone? I know it can be done. WebTV (of all things!) has in its software this ability, wherein the modem diconnects after 2 rings and then one's phone rings.