As @glark mentioned, you cannot modify attributes of a synced user using CSV import.
- Go to your directory sync config page in the Admin Panel.
- Check the box to import phones.
- Enter the names of the AD attribute(s) that hold phone information if you’re using something other than the default values.
- Perform a sync.
The phones will be imported into Duo and attached to those users.
ETA it sounds like you don’t have the phone info you’d want in Duo consistently populated in your directory? So that approach may not work for you.
If that’s the case. You can try this:
- Delete the synced directory from Duo. All the synced users become regular users (none will be deleted).
- Use CSV import to add the phones you want to these users. Import will work because they’re no longer managed by directory sync.
- Recreate your directory sync using the exact same config as before (don’t check the box to import phones).
- When you run the sync it will take over managing the users again, but leave the phones you created via import alone.