Wi-Fi Calling not working on ASUS Router

[rickysuperdog]

Wi-Fi calling is working on my Samsung S25U, router is AC68U. I can make phone call only if Wi-Fi was enabled when Airplane mode enabled.

 

[jzchen]

Somehow a search notes it uses UDP port 500 and/or 4500 as @ColinTaylor notes. Opening UDP ports seems to involve setting a static IP and then opening the port for that IP, otherwise UPnP? So does UPnP make the difference? It started being turned off by default....

 

[Tech9]

Speaking about ports and UPnP - behind NAT or CG-NAT will also affect Wi-Fi calling.

 

[ColinTaylor]

Somehow a search notes it uses UDP port 500 and/or 4500 as @ColinTaylor notes. Opening UDP ports seems to involve setting a static IP and then opening the port for that IP, otherwise UPnP? So does UPnP make the difference? It started being turned off by default....

As others have said, IPSec Passthrough must be enabled for Wi-Fi calling. No static IPs or UPnP is needed.

I find this option counterintuitive because it sounds (to me) like "enabling" it is actively doing something. In actuality it does nothing, while disabling it actively blocks IPSec traffic leaving the LAN.

These are the firewall rules that are added when IPSec Passthrough is disabled.

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 DROP       ah   --  br0    eth0    0.0.0.0/0            0.0.0.0/0
    0     0 DROP       esp  --  br0    eth0    0.0.0.0/0            0.0.0.0/0
    0     0 DROP       udp  --  br0    eth0    0.0.0.0/0            0.0.0.0/0            udp dpt:4500
   96 54912 DROP       udp  --  br0    eth0    0.0.0.0/0            0.0.0.0/0            udp dpt:500

In any case, @Spartan's problem is something different as he has this option set correctly and his phone does Wi-Fi calling at a different location.

 

[bluzfanmr1]

I wasn't aware that it's handled differently based on manufacturer. I have an iPhone and was speaking from experience, plus to quote Apple themselves:

With Wi-Fi Calling, you can make or receive a phone call if you have a Wi-Fi connection in an area with little or no cellular coverage.

 

[jzchen]

As others have said, IPSec Passthrough must be enabled for Wi-Fi calling. No static IPs or UPnP is needed.

I find this option counterintuitive because it sounds (to me) like "enabling" it is actively doing something. In actuality it does nothing, while disabling it actively blocks IPSec traffic leaving the LAN.

These are the firewall rules that are added when IPSec Passthrough is disabled.

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 DROP       ah   --  br0    eth0    0.0.0.0/0            0.0.0.0/0
    0     0 DROP       esp  --  br0    eth0    0.0.0.0/0            0.0.0.0/0
    0     0 DROP       udp  --  br0    eth0    0.0.0.0/0            0.0.0.0/0            udp dpt:4500
   96 54912 DROP       udp  --  br0    eth0    0.0.0.0/0            0.0.0.0/0            udp dpt:500

In any case, @Spartan's problem is something different as he has this option set correctly and his phone does Wi-Fi calling at a different location.

I'm forced to use IP Passthrough to avoid double NAT here with AT&T Fiber, so luckily I have some familiarity with "Passthrough". So if you disable IP Passthrough AND disable Firewall, what happens?

Another question if you please. Does this affect both IPv4 and IPv6? Sorry for being so naive....

 

[jzchen]

So SIP Passthrough AND IPSec Passthrough are needed (Google searched SIP vs IPSec): SIP allow start of call IPSec allows encrypted traffic....

@Spartan Have you enabled IPv6, (and tinkered with the default)? Really a nightmare for every settings testing....

 

[ColinTaylor]

I'm forced to use IP Passthrough to avoid double NAT here with AT&T Fiber, so luckily I have some familiarity with "Passthrough". So if you disable IP Passthrough AND disable Firewall, what happens?

Another question if you please. Does this affect both IPv4 and IPv6? Sorry for being so naive....

The "IP Passthrough" (not to be confused with IPSec Passthrough) is, from what I've read a setting on your AT&T wireless router/modem. I have no personal experience with that device. But my understanding is that it's a sort of "modem mode" for one specific device, usually a customer's wireless router.

 

[jzchen]

The "IP Passthrough" (not to be confused with IPSec Passthrough) is, from what I've read a setting on your AT&T wireless router/modem. I have no personal experience with that device. But my understanding is that it's a sort of "modem mode" for one specific device, usually a customer's wireless router.

My apologies if I've confused things. Both Passthroughs allow something to pass, whether it is WAN IP or IPSec traffic.

 

[Ripshod]

As others have said, IPSec Passthrough must be enabled for Wi-Fi calling.

Not with my setup. WiFi calling works just fine here with it disabled.
When giving advice on things like this we have to think internationally. Different countries and operators may likely have different ways of making the connection. That advice applies to everyone in this thread, including me.

 

[ColinTaylor]

Not with my setup. WiFi calling works just fine here with it disabled.

That's interesting. Perhaps some phone/operators use the term "Wi-Fi calling" to mean something different to my understanding of it, or have some sort of fallback mode. I wouldn't be at all surprised if Apple hasn't got it's own proprietary system.

 

[jzchen]

I enabled airplane mode then turned on wifi and got connected. When I tried calling I got a message saying "No network connection, turn off airplane mode before calling"

You'd probably have to try this at your friend's house to make sense of things....

 

[Spartan]

@ColinTaylor Do you think enabling WAN - Port Trigger could benefit this situation? But then there are only 2 options to add, Quick Time and Real Audio

 

[ColinTaylor]

@ColinTaylor Do you think enabling WAN - Port Trigger could benefit this situation? But then there are only 2 options to add, Quick Time and Real Audio

You can set custom ports instead of Quick Time or Real Audio. But without knowing what is causing your problem I wouldn't know what to set or whether it would help.

Who is your mobile service provider? Perhaps some other users have experience with them.

 

[nickie]

My samsung a33 running android 16 and one UI 8, runs wifi calling without showing any icon on the phone and using double-nat (could be using bridge mode, but do not need it) in a tuf-ax5400. In a different mobile phone carrier the same mobile shows the wifi calling info near the mobile network icon. It is my understanding ( and my experience) that the rules for showing the wifi calling info depends on the mobile network definitions/configurations.

 

[sfx2000]

Who is your mobile service provider? Perhaps some other users have experience with them.

@ColinTaylor - Kudos for being very patient - all of your advice here has been spot-on...

Most VoWiFi services, as mentioned earlier in the thread, should be transparent, e.g. should just work...

4500/UDP
500/UDP

IPv6 support is nice, but not needed, as most Mobile Devices can set up the L2TP/IPSec Tunnel over IPv4 - VoWiFi and it's parent, VoLTE, are IPv6 based for mobility purposes by design by the 3GPP working groups

These are ports used by Voice Over WiFi calling - these are the ports used for the L2TP/IPSec Tunnel that is created by the Phone - FQDN's for the IMS Voice GW, along with the 3GPP S101 gateway into the 4G/5G Carrier Packet Core are contained within either the SIM card (the iSIM app on the UICC), and sometimes in the Carrier Bundle (iphone) or Carrier Services (Android) files on the mobile device...

With VoWIFI Calling - a lot of things have to happen, and all the right support needs to be in place for a device to access both the carrier S101 gateway as well as the IMS media gateways...

 

[jzchen]

@Spartan If you are okay with it, please enable UPnP and try your WiFi call...

 

[Spartan]

@Spartan If you are okay with it, please enable UPnP and try your WiFi call...
View attachment 69961

UnP has always been enabled, that's the first thing I do when configuring a router, it makes no difference.

 

[jzchen]

Cellular provider can block WiFi calling. AT&T here in the US, blocks it if you bring your own phone to the network. Makes it hard for me to help troubleshoot because it is disabled on my OnePlus Open completely. It is enabled, but not by default turned on, for the iPhones we got. Currently the BE19000Ai where I tested is behind a double NAT, if that helps narrow things down...

 

[Poul Bak]

Cellular provider can block WiFi calling.

Yes, but since it works from his friends house, that should not be the issue here.
Also the phone settings should be ok (same logic).

@Spartan : You're using AIMesh. Try connecting directly to your main router (just create a test guest network) to see if that works.