A used USB phone adaptor that will allow you to make/receive both Skype and landline calls from your analogue or DECT phone. In good working conditions. Surplus to demand and looking for a new home.
It needs plugging into the USB port of your computer with the Skypemate software, which can be downloaded from the link below, but not sure if it will work with the newer versions of Windows, MacOS or Linux.
https://skypemate.software.informer.com/download/?ca1e21b