Mobile Connect runs on Amazon Connect, so you firstly need to make sure the required Amazon Connect firewall settings are setup first. In addition to that, you need to add a few extra domains for Mobile Connect to work properly.
Add these three domains to your firewall allowlist:
These domains handle Mobile Connect's specific functions that work alongside your Amazon Connect setup.
The mobileconnectcloud.com domain uses Amazon Web Services. This means the IP addresses change regularly. Amazon publishes their current IP ranges at: https://ip-ranges.amazonaws.com/ip-ranges.json. Your network team can use this file to get the latest IP addresses if they need them instead of using domain names.