As far as I know, the unit does not have a built-in Voip adapter. So you would need an adapter or a telephone that is Voip-capable by itself. VoiP is sometimes problematic via mobile phones (the mobile phone provider must allow this, stability of the line, reception quality), so I would be rather cautious. It might make more sense to have a separate, inexpensive smartphone or a Fritzbox with LTE support and, of course, a suitable mobile phone provider.