Please take a look at this document
Upgrading Avaya AuraŽ Communication Manager (Release 7.0.1 Issue 3.1 October 2016)
Migrating from Communication Manager Release 5.2.1 to Release 7.0 and later
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https://downloads.avaya.com/css/P8/documents/101014390
Procedure
1. Back up data from the Communication Manager 5.2.1 System Management Interface page.
2. Deploy the Communication Manager 7.0 OVA.
3. Restore the data on the Communication Manager 7.0 server.
4. Restart the Communication Manager 7.0 server.
5. Install the Communication Manager 7.0 authentication file.
6. Apply the Communication Manager patch for 7.0.1.