Today, if your use is enabled for UCM Calling, hybrid calling on their personal device (calling phone numbers) stops working because the Spark-RD is deleted.
This means that their Personal Device can only receive Teams calls.
Users with UCM calling still wish to make/receive calls to phone numbers using their personal device.
The workaround at the moment is to configure the device in a workspace and give it a unique DN and mailbox, which no longer makes the device personal. This is a poor solution.