Port settings for AT&T WiFi calling on secure networks
I'm answering my own question - this is something I've been researching for a while and finally have found the correct answer. Posting it here because I bet there are others who are trying to figure out the same thing. Hope this helps!
Q: What is needed for WiFi Calling to work on a secure network?
A: Requirements for functioning on Wi-Fi
- VoIP or Wi-Fi Calling Must Be Allowed on the Wi-Fi Network
- IPSEC must be allowed
- Maximum Transmission Unit (MTU) set to 1500
- Appropriate ports must be open
o Port: 500 (Protocol: UDP)
Service or Application Name: Wi-Fi Calling
o Port: 4500 (Protocol: UDP)
Service or Application Name: Wi-Fi Calling
Wi-Fi Network Throughput is another thing to consider:
- Once a device connected to one access point must it maintain at least 12kbps, and up to 72kbps.
- If throughput dips below 12 kbps the call can drop.
Wi-Fi Calling Fully Qualified Domain Names (FQDN)
Wi-Fi Calling expected to be able to hit and traverse these FQDNs:
iPhone 6s, iOS 9.1, WiFi Calling AT&T