In my case it was my SonicWall firewall that needed to be configured to allow WiFi calling to work. It's not related to the Meraki Access points. If you are having this issue I recommend you look into the VPN settings of your firewall, check if anyone using the same firewall has reported the issue and finally, reach out to their support team if you can't find the solution.   ... View more

This is likely related to your firewall, but here's why: Apple WiFi calling uses a IPSec VPN connection on UDP port 500/4500 to connect the call, it's likely that your firewall is treating this traffic as normal and changing the source port during NAT. You need to make sure that the VPN settings of your Firewall are set to preserve the connections. Reach out to your firewall's vendor for assistance. ... View more