I have many questions and possibilities for an upgrade of Call Manager 3.3(5) to 5.1(3).
Question 1 is licensing. Because the customer cannot handle downtime, I thought to build the new servers from scratch, and copy all data onto the new server by hand. (nevermind the obvious difficulties of not missing details) My customer purchased the upgrade licenses because they already have devices on their current servers. If I build new servers, instead of upgrade, can I still use these licenses?
Point 2, the customer cannot experience more than 2 hours of downtime. Ideally, they want just 30 minutes. So, upgrading the current environment in stages is out of the question. So my other possibilities are the following
1) Build the new servers with 5.1.1 in a lab environment, keeping the IP address and name of the prod servers. Copy (by hand) all configurations from old to new server. The issue with this is obviously any 'non-standard' configs of phones or users that have been changed over the past 4 years. Then just disconnect network from old server to new server. Hope that all devices upgrade and register.
2) Use a new server (purposed for Unity) to install the existing version 3.3(5) and use BARS to build it exactly like production. Then incrementally upgrade that server to 4.1(3) then to 5.1(3). The issue with this is obtaining proper software and OS disks and all the upgrades in between.
Does anyone have any suggestions as the the easiest method and/or the one with least downtime?
In addition, I am upgrading Unity 4.0.4 to 5.X But that's another issue.