Nspanel pro call each other

Dear support
I have two NSPANEL PRO and want to call each other.
However on one Panel there is the call button on the main screen, but on the other one there is no call button. I tried to reinstall software, have updated to the latest version, v1.7.0 or so but nothing works.
Could you please solve the issue?

I also have 2 NSPanel Pro’s with both v1.7.0 on it, but both don’t show a calling button at all. I wonder how eWeLink imagined calling between both NSPanel Pro’s should work.