Karoo say that does not work. I don’t know if only because the unit has no mic, or if there are other tech limitations (e.g. data transfer protocols).

I suppose Bluetooth headphones with mic might be the workaround for the not having one, but are all BT protocols the same and support audio? It’s all beyond what I know about, but Hammerhead did not equivocate about calls not working on the unit either natively or via app.