Fritzbox Sip Call

I´m looking for one node which just can make a SIP call to fritzbox.
Or any other solution.

What i want to do:
Just simple: one ESP ist connected to 2 Door Belt.
If button pressed esp sends a mqtt comand to ring.
Node red get this information and send a sip call to some of the phones in the fritzbox.
of course i can see if door one or door 2 is calling.
the best solution would be, i could totaly use the doorbelt setup in the fritzbox.

who know if something like this exist and how to do ?.

I think you can use the node-red-contrib-fritz node for that.
No need for sip, you call an intern number

thanks for your information. But on this tool i dont find how to call.

I second the question. I need to have the possibility to start an internal call, but am lost as how to do this.
Background: I need an alert button for my elderly relative. On pressing a button (connected to an esp8266 wifi module) and contacting node red the handsets have to ring.

Thanks for the help in advance.