Samsung OneUI 8.5 and VoWiFi / wifi calling

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tanivula

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#324912 12-Jun-2026 11:30

Hey guys, just doing some digging and seem to have found an issue with a couple of Sammy devices (S24 / A57) that have calling issues (making & receiving) with WiFi Calling enabled with WiFi set as preferred.

Both devices were connected to Spark at the time, so trying to figure out whether this is related to Spark or the update. I haven't got other network SIMs with me to test if this is limited to Spark.

My phone currently doesn't seem to be able to use WiFi calling (the logo doesn't change in the notification area from VoLTE). Looking at my call log, I can clearly see the last WiFi call was made on the 5th of June. I recall there was a Samsung update around that weekend.

Both devices are on OneUI8.5 so I was hedging my bets on that.

Does anyone else running a Sammy device with WiFi set as preferred in WiFi calling seeing this problem?

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#3502291 12-Jun-2026 11:37

My S23 Ultra is having the same thing. Quic as ISP and unifi router/APs.

jamesrt

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#3502294 12-Jun-2026 11:40

Hi,

Samsung A56, OneUI 8.5 with a Spark physical SIM, wifi calling turned on, and set for WiFi Preferred also still seems to be using VoLTE according to the icons in the status bar.

Sim slot #2, just in case that makes a difference.

Sim #1, 2Degrees, VoWIFI is fine.

tanivula

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#3502296 12-Jun-2026 11:51

Thanks for confirming guys 👌🏽

I have tried to raise this with Spark.

@jamesrt I would recommend you either disable it OR set it to mobile preferred (or enjoy the peace and quiet - which was what I have been doing for a few days!)

jamesrt

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#3502298 12-Jun-2026 11:56

Thanks; it's normally on mobile preferred, tbh; I just changed it to test.

freitasm

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#3502300 12-Jun-2026 12:04

Just in case, all of you guys have ALG IPSec passthrough enabled on your routers?

Other than this, I see VoWiFi is another area where things work or not. In my case, with an Oppo on 2degrees I sometimes answer an incoming call, I can hear the caller but they can't hear me, for about four seconds. A trace has shown the call setup failed sometimes, and blame was placed on the handset firmware...

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tanivula

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#3502310 12-Jun-2026 12:10

freitasm:

Just in case, all of you guys have ALG IPSec passthrough enabled on your routers?

Other than this, I see VoWiFi is another area where things work or not. In my case, with an Oppo on 2degrees I sometimes answer an incoming call, I can hear the caller but they can't hear me, for about four seconds. A trace has shown the call setup failed sometimes, and blame was placed on the handset firmware...

I haven't bothered checking - it was something that was working without fault a couple of weeks ago and there have not been any (LAN) network changes on the WiFi networks I am usually connected to (home or work).

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#3502311 12-Jun-2026 12:17

It makes sense. Things just don't "change".

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roderickh

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#3502319 12-Jun-2026 12:33

Good spot - I thought I was having weird issues, S26U on Spark.
Work actually ported us to OneNZ recently, and now on WiFi calling settings there is no option to be WiFi or Mobile preferred.

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#3502370 12-Jun-2026 12:58

@tanivula I am dealing with SparkNZ around Wi-Fi calling issues / failed call setups / dropped calls / incoming call going direct to Voicemail

It is a known issue and started just over a week ago!

Is it impacting all of our work SparkNZ mobiles right across NZ

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#3502371 12-Jun-2026 13:02

Wi-Fi calling registration is also dropping off

Issues line up to when Spark cut over to a new Core network

tanivula

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#3502708 13-Jun-2026 22:11

got a message from Spark that they made a profile change to my number and seems I'm all good now.

I've queried to tell them it affects others too 🙄

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#3502710 13-Jun-2026 22:25

@tanivula The issue is not just your mobile number. The staff member that messaged you did absolutely nothing to your mobile profile

They are talking kaka!

tanivula

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#3502711 13-Jun-2026 22:27

might be kaka, but my phone is connecting to VoWiFi and calls are working fine.

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#3502712 13-Jun-2026 22:30

tanivula:

might be kaka, but my phone is connecting to VoWiFi and calls are working fine.

@tanivula Spark are working on resolving issues with the setup of the new Core network

It is like having a brain, liver, heart transplant in a single operation and just takes time to get things right / fine tuned

taneb1

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#3502713 13-Jun-2026 22:43

Have been seeing this intermittently before the 8.5 Upgrade (S25+ started back in April, or at least thats when I reported it)
Calls going straight to voicemail, sporadically failing to set up, the handset showing the incoming call 15+ minutes after when it actually happened.

Response I got was that it was a handset issue and to set the WiFi Calling setting to Mobile Network Preferred (which eliminates the whole point of having WiFi Calling enabled...)
Ended up leaving it like this as couldn't deal with missing calls when on call / people thought I was ignoring their calls.

Any comments made are my personal views and does not represent those of my employer

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