An Evolution Data Only (EV-DO) service is provided by a network interfacing a wireless public network and a wired/wireless private network so that an EV-DO call is transmitted via the private network when an EV-DO service is intended to be provided via the private network. An arbitrary terminal sets up an identifier indicating which of the private and public networks is to transmit the EV-DO service and the identifier received from the arbitrary terminal is retrieved to request the EV-DO service via a corresponding network based on the retrieved identifier. Consequently, the EV-DO call is forwarded via the selected network, and since an EV-DO call is forwarded via the private network by modifying the system without changing each user terminal, no additional expense is necessary.