I get really poor mobile reception in my flat, so I've investigated the SmartCall app.
My problem though is that I have unlimited calls on my mobile, but only the M package weekend calls on my landline - so I don't want the app to use my landline minutes, which will cost, but my mobile minutes, which won't.
However I can't see a way to do this? Am I missing something? (Someone I know on Three has a small box which plugs into their router and routes their regular mobile calls over wifi/broadband, so clearly it can be done, and there's no technical reason why it should be linked to a landline account).