The phased approach takes the conversion one step at a time. The implementation requires a thoroughly thought out scenario for starting to use the new system. And at every milestone one has to instruct the employees and other users. The old system is taken over by the new system in predefined steps until it is totally abounded. The actual installation of the new system will be done in several ways, per module or per product and several instances can be carried out. This may be done by introducing some of the functionalities of the system before the rest or by introducing some functionalities to certain users before introducing them to all the users. This gives the users the time to cope with the changes caused by the system.