Three businesses into one tenant, with zero user downtime
A three-party merger brought into a single Microsoft 365 tenant and network over nine months, without a single day of lost working time for users.
- Client
- UK chartered surveying and property consultancy
- Role
- Technical Project Manager and Migration Engineer, via Tela Technology
- When
- 2025 to 2026
0hours of user downtime
22sites
471users
613endpoints migrated
27servers
The situation
Three firms had merged and needed to operate as one business: one tenant, one network, one way of signing in. Staff had to keep working throughout.
What I did
I led the project and did the technical delivery on the same engagement, acting as the client-facing solution designer and third-line escalation point.
- Mail and files. Migrated mailboxes, shared mailboxes, archives and OneDrive with BitTitan MigrationWiz, and delivered the SharePoint Online and Teams migration.
- Devices. Moved all 613 endpoints tenant-to-tenant with PowerSync Pro, including Intune setup, application packaging, automated deployment and antivirus replacement.
- Identity. Completed Active Directory, Entra ID and DNS changes, and moved every user to a single MFA platform, WatchGuard AuthPoint.
- Network. Deployed and upgraded firewalls, access points and Hyper-V servers across 22 sites, and reconfigured the site-to-site VPNs for the merged estate.
- Close-out. Implemented cloud backups, achieved Cyber Essentials for the merged organisation and decommissioned the source tenants.
The outcome
The merged business runs on one tenant and one network, is Cyber Essentials certified, and users lost no working time during the move.