We had to rebuild a Subscriber in a 4.3 cluster. We installed with the OS 2003.1.1 disk and then upgraded to 2003.1.5 and then SR19. After installing CUCM everyting looked fine. Now we are getting prompts to Activate Windows. I have never seen this happen with a CUCM install in Windows. I have tried a couple of known good windows 2003 product keys but they don't work. Obviously we can't call TAC on this. as 4.3 is out of support. We only need to get by for another month until the new UCS comes in for the upgrade. But the windows activation will expire before then.
The paper envelope that the OS DVD came in would have had a Microsoft CoA sticker and key on it. Cisco had a special Embedded/Telecom edition agreement with Microsoft so normal Standard/Enterprise license keys won't work. It's illegal for any of us to give you a key. You may want to reach out to your Cisco AM/SE; they might be able to find a temporary solution for you.