-Direct Changeover
The old system is stopped completely, and the new system is started. All of the data that used to be input into the old system, now goes into the new one.
-Parallel Running
The new system is started, but the old system is kept running in parallel (side-by-side) for a while. All of the data that is input into the old system, is also input into the new one.Eventually, the old system will be stopped, but only when the new system has been proven to work.
-Phased Implementation
The new system is introduced in phases (stages, or steps), gradually replacing parts of the old system until eventually, the new system has taken over.
-Pilot Running
The new system is first of all piloted (trialled) in one part of the business / organisation (e.g. in just one office, or in just one department). Once the pilot system is running successfully, the new system is introduced to the all of the business / organisation.