You are trying to install the wrong package. You do a build of the _r packages and install the _d packages (unless something has changed). Either way try to install one, if it doesn't work then install the other

Once you get it installed, there should be a sample terminal application that you can look at.

As mentioned Synapse does have some support for TAPI with modems, but I don't think it supports the actual control of dialing the modem.