Infusionsoft IP address range

We have a running application that has an API. We have registered our API endpoints in Infusionsoft to receive web hook calls.
It is all working well in a development environment however to move this in to production environment our client has to know exact IP addresses that will make calls to our API so it can be whitelisted.
The security of the servers is very important to our client.
What is the IP address range that Infusionsoft uses that we will allow?

We have instances of our services operating out of Google Cloud, deployed around the globe for performance reasons. We do not commit to a static range of IP address blocks for our services, so you won’t be able to rely on a whitelist by IP, although you should be able to whitelist by domain (*.infusionsoft.com, *.keap.com).

Hi Tom,
Thanks for looking into this.

I have checked with the IT guys and they mentioned that this wont’ work because they have had a look at the hook calls coming into the test servers and they were coming from googleusercontent.com
So whitelisting the domains won’t work …