CallManagers should not be in domains. They belong in Workgroups if they are CM 4x.

If Unity is setup as Voicemail Only, It has it's own domain, own Exchange server, etc.

To migrate to your production domain (possibly you have Exchange for email, domain controllers, servers, etc running) you need a complete rebuild of Unity.

Basically, you will need to install a new Unity server in your domain, (purchase VM to UM license upgrades) attach to your existing Exchange Store and users.

Migrate Voicemails from old server to new server. This can be done with exmerge (MS tool) or with tools at ciscounitytools.com. DIRT will help, but if the Alias's are not the same, you have to manually map them.

Setup your CallHandlers again, etc.

It's a fairly long process because you are basically re-installing from scratch into the new domain. With any Windows AD enviroment, you cant just move Exchange servers between domains that easy. And renaming Domain controllers, domains, DNS, it gets fairly messy.

There a few documents on Cisco website for migrating from VM to UM enviroments for Unity.

As for CCM, you are probably not using anything, or are using AD authentication for CM4? If it's CM5/Cm6 you using LDAP, which is easy to change, but then you have to re-associated device to user ID, etc.

Basically, there is no reason you can't, but you have to understand clearly how the backend of all these servers work with AD.