The project plan identifies milestones at which go/no-go decisions are made. These milestones conform to the deliverables. No milestone are considered complete until a review has been conducted, the work completed to-date, and the work planned for the next stage has been understood and accepted by the Project Manager and the client.
These milestone reviews further ensure that inter-project communication has taken place, end client have been involved and the process is sufficient prior to reaching completion of the phase.
The Project Manager is responsible for identifying the milestone review points and for structuring the reviews. Milestones or deliverables are independently reviewed, approved and involves the Project Sponsor/ client.