Configuration guide for WiFi calling?

Hey all,
I'm trying to set up AT&T Wifi calling and was wondering if there is a guide for setting it up with OpenWrt? AT&T provides this support article for what requirements are needed to get it working, but I'm not sure what firewall rules need to be enabled and how to make the traversal of certain FQDN's happen.

Have you tested your phone yet?

I have phones from multiple carriers, I did nothing to make the WiFi calling work.


It says it is enabled on my S7, but I'm getting the same poor reception and dropped calls at my house where I have poor cell service. If I'm using my phone standing next to my router I'm still getting poor reception so it seems to me that wifi calling isn't working properly.

I also had to do literally nothing on the router to get it to work. It is possible that uPnP needs to be enabled, although I'm not sure if that matters or not.

I do know that on my phone it was necessary to explicitly turn wifi calling on (I use an iPhone). It also sometimes takes a little while for the phone to switch to wifi calling after the device generally connects to my wifi network. When wifi calling is active, it is immediately clear because I see "VZW Wifi" at the top of my screen (in the past when I used AT&T, it also had AT&T Wifi indicators).

If it is not working for you, you might contact your carrier to ask them if there is anything you need to do on your phone, account, or local network.

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I'll try re-enabling UPnP; and if that isn't it I'll try messing with my S7 again, even though I did explicitly turn wifi calling on with the icon indicating as much. I might just have to contact AT&T to see if they can do any troubleshooting on their end. Anyway, thanks for commenting and confirming that it shouldn't be anything to do with my router config.

If you install tcpdump-mini, you should be able to see the IPSEC traffic and determine if/that your router is working just fine. Look for it on your "LAN" and then on your "WAN". UDP port 4500 and UDP port 500, IPSEC. tcpdump will probably render it as "UDP-encap: ESP"

Port 143 TCP is probably to check for voice mail or the like.

All connections are initiated from your phone so "normal" NAT configuration should work, as long as IPSEC isn't blocked.

The "big guys" design things so that it "just works" in the majority of situations a consumer would be in. That definitely includes consumer all-in-one wireless routers. Significant savings for them to take you off their towers and onto somebody else's infrastructure.

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