UPC router no problem. So it should also work with Swisscom.

All analogue phones can be connected to the Swisscom router, i.e. the base station of the DECT phone has an analogue line to the router and a power connection for charging, the phone only has a DECT radio connection between handset and base station. The E720A is one of these.

Direct connection means a base station with power connection only, the DECT radio connection is between the handset and the Swisscom router. On Gigaset phones, these models are labelled HX.

This connection enables some convenient functions, but this is not possible with an answering machine, unless you use the Combox for this.

I think the E720A is a successful device, easy to use and feels good in the hand. Unfortunately, Gigaset has now been sold to its competitor, so who knows what will happen next ...

I have a UPC / Sunrise router with analogue output and it worked perfectly. I am convinced that it must work in exactly the same way with a Swisscom router. It simply can't be a VoIP device, it doesn't work with an analogue router connection.
And another thing: this DECT phone is awesome.