1. In-Place Server—Hybrid Migration Unified CM 4.X to 7.1
Existing Backup Subscriber
Existing backup subscriber is not the call processing server
Be careful about duplicate IP addresses
New Publisher TFTP 2
Can use new IP addresses in new cluster
New DHCP option 150 points to new TFTP server
Phones can re-home to new TFTP and new active subscriber *Make sure existing 4.X active sub is off
Existing TFTP
New Active Subscriber 3
New backup subscriber is online for redundancy
Existing Active Subscriber
New Backup Subscriber 4
Save the Existing Publisher for last in case of downgrade
Once upgrade is deemed acceptable
Change DHCP option 150 back to new TFTP server
Revise activated services as required
Existing Publisher
New TFTP 1