Transmission
Trading partners are free to use any method for the transmission of documents. In the past one of the more popular methods was the usage of a Bisync modem to communicate through a value added network (VAN). Some organizations have used direct modem to modem connections and bulletin board systems (BBS), and recently there has been a move towards using some of the many Internet protocols for transmission, but most EDI is still transmitted using a VAN. In the healthcare industry, a VAN is referred to as a "clearinghouse".
Read more about this topic: Electronic Data Interchange