Wifi Calling with iPhone 8 Plus via BT Home Hub 5

[WH1234]

Are there any known issues with the reliability of Wifi Calling using an iPhone 8 Plus via a BT Home Hub 5?

My home is in an area where the mobile phone signal is very poor on all networks, so WiFi calling is crucial. I have recently moved 2 phones - mine and my wife's - from Vodafone to BT Mobile. So far my Samsung Galaxy S10 seems to be handling WiFi Calling okay, but my wife's iPhone 8 Plus is very unreliable, with frequent connection failures and dropped calls.

We have fibre broadband via a BT Home Hub 5 with download over 30Mbps, upload of 6Mbps and latency of 23ms. This should be easily adequate for WiFi Calling.

We have tried using the iPhone in airline mode, to avoid the potential issue with the phone trying to switch between mobile network and WiFi during calls.

With the iPhone in the same room as the Home Hub (so that the WiFi signal strength is definitely not an issue), and showing WiFi Calling active, the following issues are experienced with the iPhone:

1) Outgoing calls do not connect. No ringing is heard and "Call Failed" is shown on the screen.

2) When the iPhone is an in a state of not allowing outgoing calls, any callers to the iPhone are told that it is not accepting calls.

3) Active calls are disconnected at random intervals. Sometimes it is possible to re-establish the call immediately, sometimes the iPhone is in a state where issues 1 and 2 are present.

Could there be something wrong with the settings on the iPhone? It is fully up-to-date.

Could it be that the Home Hub 5 cannot properly handle WiFi Calling from an iPhone? Do BT need to provide a more modern router?

I am really disappointed with BT overall. BT Mobile are not providing me with a usable signal at my home (contrary to what their network coverage site indicates), nor are they providing a reliable WiFi Calling solution for the iPhone via a BT broadband connection.

[Dode]

Had an iPhone 8 and had no problems with Wifi calling. Make sure Wifi calling is on under Settings>Mobile Data and that location Services is on under Settings>Privacy. Good idea to restart the phone after that.

[WH1234]

Thanks @Dode. Are your calls being routed via a BT Home Hub 5? Obviously BT are pushing their customers to pay for their new Halo offering, and I'm wondering if WiFi Calling is not properly supported on the Home Hub 5.

[imjolly]

WiFi calling is nothing to do with the router you are using as long as you have a WiFi connection to iphone

[WH1234]

@imjolly The WiFi connection between the iPhone and the Home Hub 5 seems solid, and I've not seen any issues with the iPhone's connectivity to the internet. The phone is able to run audio/video calling apps (FaceTime, WhatsApp, Facebook Messenger) without any issues, so I don't think the internet connection has an intermittent throughput issue. The only problem I'm seeing is with WiFi Calling.

At this point in time I can't rule out the possibility that there's an issue with the way in which the Home Hub is configured to handle the WiFi Calling data being passed to/from the BT Mobile servers. The Home Hub is running the default configuration, I haven't done anything silly with it. I suppose the only way I can rule out my Home Hub as the source of the problem is to perform WiFi Calling via a different WiFi connection - unfortunately due to covid there are limited opportunities to spend much time away from home.

It is strange that the Samsung S10 doesn't seem to have a problem. I suppose the Samsung WiFi Calling software implementation will be different from the Apple one, and it is possible that the Apple implementation is exposing an issue which the Samsung implementation doesn't.

I also can't rule out the possibility that my (wife's) iPhone has a fault. But as I said, it doesn't have any issues with any other functionality, only the WiFi Calling, so it seems unlikely.

Given that the iPhone 8 and the Home Hub 5 are both quite old technology, I was hoping that there was a known issue with a known fix. Sadly it looks like that's not the case. I probably have no choice but to try and get BT to take responsibility for resolving the issue. Unfortunately I fully expect that they'll fob me off and bounce me back and forward between the Mobile and Broadband divisions.

[Dode]

If the Hub is running "the default configuration" you could try turning smart setup off and split the 2.4 and 5Ghz SSIDs. There's instructions somewhere on the help pages for that. It may just be jumping between the two. Anything I connect to Wifi always seems to be happier on the 2.4GHz. Worth a try.

[stevebrass]

Which iOS in the iPhone on?

[Les-Gibson]

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@WH1234wrote:

We have tried using the iPhone in airline mode, to avoid the potential issue with the phone trying to switch between mobile network and WiFi during calls.

You shouldn't need to do that if Prefer Wi-Fi calling is enabled

2) When the iPhone is an in a state of not allowing outgoing calls, any callers to the iPhone are told that it is not accepting calls.

Just a thought, is this a Wi-Fi calling issue or an issue with the phones power management?

Could there be something wrong with the settings on the iPhone? It is fully up-to-date.

I don't know what Fully up to date means on the iPhone8, you need iOS 11.2 as a minimum

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One other thought, have you tried disabling MAC randomisation on the phone

[stevebrass]

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@Les-Gibsonwrote:

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@WH1234wrote:

We have tried using the iPhone in airline mode, to avoid the potential issue with the phone trying to switch between mobile network and WiFi during calls.

You shouldn't need to do that if Prefer Wi-Fi calling is enabled

2) When the iPhone is an in a state of not allowing outgoing calls, any callers to the iPhone are told that it is not accepting calls.

Just a thought, is this a Wi-Fi calling issue or an issue with the phones power management?

Could there be something wrong with the settings on the iPhone? It is fully up-to-date.

I don't know what Fully up to date means on the iPhone8, you need iOS 11.2 as a minimum

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One other thought, have you tried disabling MAC randomisation on the phone

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Hence my asking about the IOS version. Great minds..................

[WH1234]

Thanks for all the suggestions. I can definitely dream up theories why each of them would work. But unfortunately, still no success 😞

The iPhone was running iOS 15.1, but I've now updated it to 15.2. This is the latest iOS. So despite the iPhone 8 being a bit old now, Apple are still supporting it.

I don't really need 5GHz WiFi anyway, so I've completely disabled it on the Home Hub. I've also put the 2.4GHz WiFi on to a fixed channel. Running a WiFi scanner on my PC shows that the channel isn't busy.

The MAC randomisation option is a good possibility. I'm not sure what the option does exactly - whether it randomises the MAC each time the iPhone reconnects to a known access point, or whether it uses a randomised MAC at the point the phone is connecting to a new access point. It's easy to imagine that if it randomised the MAC on each reconnect it would confuse the BT Mobile servers. Anyway, I disabled the option (Apple call it "Private Wi-Fi Address").

With all the changes I was quite hopeful because my wife managed to make a 20 minute call without it being dropped. However, a later call got disconnected after around 10 minutes, and it took a few attempts to get it to reconnect.

Power management is a good line of investigation. It's possible that iOS is restarting the Phone app because it is using too much power. I'll have to try and find out whether there's any options to prevent the iOS power management from interfering with specific apps.

Also, I think I really need to find out how the iPhone performs on a different WiFi access point. If it continues to misbehave then I might have to consider upgrading the phone.