A method of processing incoming digital telephone calls from remotely located call originators which are destined for receipt by a host computer system. The host computer system is linked to the telephone network by a network access server. The call originators may be any type of data terminal, such as a personal computer or a credit card swipe, which is connected to a modem. The network access server extracts control signals imparted onto the telephone line and correlates the control signals with particular communications, routing or applications protocols identified with the call originators. The modem in the network access server which answers the call is configured during the call connect process and placed in a compatible format for the communications protocol of the incoming call. This dynamic custom configuration of the modem reduces the overall telephone call connection and processing time. The control signals may also be used by network access server for customized call routing or by the network access server or host computer system to run specialized application programs. The method is particularly suitable for use by large enterprises handling a high volume of incoming calls in which data is transmitted to the host computer system according to a variety of different communications protocols, or where the implementation of different routing paths or applications programs is desireable according to the identity or classification of the call originator.