Does Cronofy provide fixed IP addresses for calendar service traffic?
Cronofy uses fixed IP address when communicating with calendar servers according to the data center the calendar service is connected to.
Your application vendor will be able to tell you which data center applies to your integration so that you can set your firewall rules accordingly.
220.127.116.11 18.104.22.168 22.214.171.124
126.96.36.199 188.8.131.52 184.108.40.206