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Deployment phases of Office 365


Applies to: Office 365 Enterprise

Topic Last Modified: 2013-09-05

Summary: Describes the Plan, Prepare, and Migrate phases of Office 365, sample deployment schedules, and entrance and exit criteria for deployment checkpoints.

Microsoft recommends that you expedite your Office 365 deployment by proceeding in three distinct phases: Plan, Prepare, and Migrate. Organizing your deployment according to these phases provides your project team with high-level timeframes that control the pace of the deployment while keeping individual tasks serialized. It is common for tasks outlined in the Plan phase and Prepare phase to occur simultaneously and for tasks in the Prepare phase and Migrate phase to overlap.

The following figure depicts the phases and key activities for organizations deploying Office 365.

Describes the Plan, Prepare, and Migrate steps

Office 365 deployment phases

To help your organization plan your deployment project according to the Plan, Prepare, and Migrate phases, see Deployment planning checklist for Office 365.

The following figure illustrates a high-level sample schedule for an Office 365 deployment project that involves migrating 8,000 users.

Describes the tasks in each checkpoint

Office 365 sample deployment schedule

The number of weeks required to complete all migrations will vary based on a number of factors including number of users you are migrating and the complexity of your organization’s environment.

To ensure a successful Office 365 deployment, you should periodically review and assess the key milestones within the deployment project. The following checkpoints are sample entrance and exit criteria to use while moving through the deployment process. If your deployment has not completed all exit criteria tasks included in a checkpoint, the deployment should not move forward on the project until all those tasks are completed.

Prior to moving forward with your Office 365 for enterprises deployment, you should ensure your organization has completed the following entrance criteria:

  • Review of Office 365 service descriptions to ensure solution alignment. Your organization should not move forward with its deployment until all aspects of the service have been evaluated for alignment with your existing business and IT requirements.

  • Review of your Active Directory environment. Your organization should ensure that your Active Directory complies with the requirements for Office 365. During your review, you should keep in mind that hybrid deployments only support email coexistence with a single Active Directory forest and that the directory synchronization service requires a support exception for synchronization of more than 50,000 users.


You can use the checks available in OnRamp for Office 365 to help assess how many total Active Directory objects, and specifically user objects, are stored in your Active Directory forest.

Purchase of Office 365 for enterprises user licenses. To provision users for Office 365 services, your organization will need to have valid user licenses available to assign to users.


Ensure that the deployment project scope and schedule are well understood by all your project team members from the Project Manager to the Executive Sponsor.

Checkpoint Exit Criteria

1. Identified plans for the following items:

  • Migration

  • Mail-enabled applications

  • User identity and account provisioning options

  • On-premises infrastructure and hardware requirements

  • Network bandwidth requirements

  • Client operating systems and client applications

  • Service desk training

  • End user and administrator training

  • End user communication strategy

2. Completed the following activities:

  • Customer kickoff meeting with agreement on the following:

    • Dedicated deployment project management team

    • Review of each workstream, milestone activities, and timelines

    • Commitment from all workstream owners on milestone timelines and dates

Customer sign-off on Plan Complete milestone.

Ensure all configuration and preparation tasks are completed.

Checkpoint Exit Criteria

  • Remediation of directory synchronization errors

  • Specific service configurations completed

  • Office 365 Desktop Setup package deployed

  • Email migration and coexistence tested and validated

  • Service desk integrated

Migration schedule is completed.


  • Velocity mailbox migrations begin.

  • Criteria to stop the deployment is defined and agreed upon.

Checkpoint Exit Criteria

  • Mailbox migration is completed.

  • Plan is in place for deprovisioning of on-premises services (unless hybrid scenarios exist).

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