Chintan, now I am stuck. I deinstalled the APP through normal channels. Reinstall however does not work, because the store says: "This App is installed". The Insider Preview status of the L830 is still "Fast". It looks as of the deinstall process left some dead bodies in the phone. What is your suggestion?
I could try to go out of Insider Preview and try to install "normal" Skype. Or after getting out of Insider Preview, wait a moment, re-enter Insider Preview and try again installing "Skype Preview".
ADDITION: "Normal" Skype cannot be installed, as the Store defaults automatically to "Skype Preview". I have stopped Insider Preview, hoping the normal Skype would then be available again in the store.