1. An ISDN call-processing system comprising: A) an input device for generating behavior signals that represent inpulse rules that specify behavior to be followed in response to receipt of ISDN data-channel messages, wherein some of these rules specify information elements; and B) a switching system, including: i) an input port coupled to the input device for reception of the behavior signals therefrom; ii) at least one network port adapted for connection to a respective network line for reception therefrom of ISDN data-channel messages that reference respective calls; and iii) a host port adapted for coupling to a host computer for reception therefrom of host input signals that associate inpulse rules with respective calls and for transmitting to the host information requested by the information elements specified in the inpulse rules, the switching system storing the inpulse rules represented by the behavior signals and responding to reception of ISDN data-channel messages from the network line in accordance with the thus-stored inpulse rules.