Alright, yay!
Make sure that IP address is fixed or as I suggested, use a proper fully qualified domain name that is resolvable in your network (like the fritz.box example, if applicable). Wouldn’t be nice if this stops to work after a while. 
thank you very much for your help and this advise! i will follow it
Unfortunately I just can’t get it. In my home assistant there is only the state on/off and not true/false
I took over the automation exactly, ip, token changed but nothing happened when ringing.
Can someone help me here again?
It’s also possible over ifttt!