Let KaKu doorbell also trigger my phone

Configuration
1

I want my KaKu doorbell to trigger my iPhone so when I’m not able to hear it I get a message.
I found a config to add the doorbell, but nothing happens. No doorbell in the system. I rebooted the system.

See config below

switch:
- platform: rfxtrx
  automatic_add: True
  devices:
      0b11000f022eff9601040f70:
        name: Deurbel_Voor
        fire_event: True
  switch.deurbel_voor:
   friendly_name: 'Deurbel_Voor'
   icon: mdi:bell-ring
   assumed_state: false
2

I have no experience with CoCo (like it’s translated to English), but just to rule things out.
I took a quick look here: RFXCOM RFXtrx - Home Assistant

Do you have the appropriate hardware (receiver) connected to your HA.
If so, and you added the integration, your doorbell button should be automatically detected if you checked that box.