In a session-based or synchronous synchronization scheme, synchronization occurs in real time over some sort of direct communications link. For example, the connection can be over a modem, network, or radio modem. Remote sites connect at intervals of seconds, minutes, hours, days, or weeks.

A session-based synchronization process is analogous to a telephone conversation in which all outstanding issues at both ends are resolved. The process follows a particular format. A MobiLink remote site begins by opening a connection to a MobiLink server and uploading a complete list of all the changes made to the remote database since the previous synchronization. Upon receiving this data, the server updates the central database, and then sends back all relevant changes. The remote site incorporates the entire set of changes, then sends back a confirmation and closes the connection.