Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Dear Sachin Ameta,
Good day! Thank you for posting to Microsoft Community.
To enroll your 6000 hybrid AD-joined devices in Intune for MDM deployment, you'll need to ensure that each device has an appropriate Intune license. Each device that you want to manage with Intune requires a license. This can be an Intune standalone license or a license that includes Intune, such as Microsoft 365 E3, E5, or Enterprise Mobility + Security (EMS) E3/E5. Since you mentioned that, you have 700 licenses for Security + Office E3, assuming these are Microsoft 365 E3 licenses, they include Intune. However, with only 700 licenses, you can only manage 700 devices. you can refer to Assign Microsoft Intune licenses | Microsoft Learn and Licenses available for Microsoft Intune | Microsoft Learn.
In the meantime if you need further details, as your query is related to Microsoft Intune Enrollment and since Microsoft has specific support channel resource for certain different support scope and attributes, we are belong to Microsoft Forum Community mainly focused on Micrsoft 365 Exchange online only. Therefore, we provide some limited knowledge about some aspects of Microsoft Intune related scenarios. For further query, we have a dedicated team with special expertise in Microsoft Intune Enrollment related queries, so would you mind to connect and place your query on our dedicated Microsoft Intune Enrollment - Microsoft Q&A? We believe they will give you accurate and efficient solution for your concern.
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Libeamlak | Microsoft Community Moderator