Abstract: In order to transfer data via a switched network that provides a wide range of network services, the users must establish a circuit or network connection and establish a data link connection. The circuit or network connection provides the physical connection between the users and data link connection provides the protocols and procedures for the transfer of data. Because the network provides a wide range of services, the users, typically by prior agreement, designate a common data link protocol to facilitate the transfer of data. A data link connection will not be established if the users are not using the same data link protocol. A method and apparatus are disclosed which permit a local system to detect the data link protocol used by a remote system. The invention provides a method for detecting the data link protocol used by the remote system when the remote system initiates the data link setup and a method for detecting the data link protocol when the local system initiates the data link setup.