Hi @HelenBunchLive
The post shared by Jeremie gives a good understanding of how (none) is evaluated in Amplitude.
When Carrier = (none) , it mostly means that this property never came in with that event. i.e. absence of that user property when the event was fired.
When Carrier = Unknown, it means that this value was explicitly captured as “Unknown” during that event.
You can pull up the raw event data for any one of those events to validate this in the user’s event stream.
I haven’t found any thing in the docs which explains the caveats of how Amplitude captures the default Carrier property via the SDKs.So not quite sure about the true meaning of “unknown” for Carrier.