@Raphael Nascimento , From your description, I know the Phone number of some Android Enterprise fully managed devices is not shown in Intune. Based on my research, one possible cause can be that certain SIM cards will not write the data and phone number won’t get reported by Google.
https://learn.microsoft.com/en-us/mem/intune/remote-actions/device-inventory
We can insert the SIM card to other device like apple phone to see if we can get the Phone number.
If there's any update, feel free to let us know.
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