About Wi-Fi Assist - Apple Support which discusses the opposite situation.
Wi-Fi Assist does not switch to cellular
T-Mobile, iPhone 16 and 13. Good Wi-Fi coverage with three eeros. Recently switched internet providers and no change.
Frequently one bar (sometimes two). On incoming call phone won’t ring (we have a shared incoming number via Google Voice) so can see one phone will ring and the other not at times.
This has gone on for years and have checked the settings. I can force a switch by killing the cellular connection, but that doesn’t work for incoming calls not ringing and is awkward for an ongoing call since you have to make the change than restart the call—the situation is a poor connection.
And way to assure Wi-Fi is preferred while in our house? Short of killing cellular every time we enter house. We aren’t going to remember to make that switch.
It can be related to the mobile phone carrier if it works or not. Works on my private iPhone but not on the one from my employer. They use different carriers.
Perhaps there is something to learn from the Apple support pages.
As far as I know, there is no iOS feature to automatically switch to Wi-Fi in the presence of a weak or absent cellular signal. iOS should automatically join any Wi-Fi network to which you have previously connected, unless you disabled automatic joining for that network:
Wi-Fi calling (placing normal voice calls over your Wi-Fi network) is a carrier-specific feature. If your mobile service provider offers it, the setting will be in the Cellular settings:
When that feature is on (at least with my Verizon account), all voice calls will go over Wi-Fi whenever you are connected to a Wi-Fi network with sufficient bandwidth, even when you have a perfect cellular signal.
A phone not ringing at all is more likely a carrier capacity problem, not a weak signal problem. Which means it’s even more out of your influence (sorry)
The screenshot shows Wi-Fi calling Off.
Re other comments. My Wi-Fi shows connected, T-Mobile just doesn’t switch to Wi-Fi.
My wife’s phone will ring and mine not. I doubt capacity is the problem, this is a residential area.
@ NiklasB Thanks. I had all those settings. I guess T-Mobile is the problem. Make a call with Wi-Fi Calling - Apple Support
I can turn off cellular manually and it works fine. I just want it to switch with a weak signal. Too subtle. This is to the benefit of T-Mobile to make this work. Would reduce their load. Oh well.
Yes. Because I normally don’t use it. Usually only if I’m traveling internationally and would otherwise incur large roaming charges. But since you asked, here’s a shot with it turned on:
When Wi-Fi calling is active, my carrier-ID string (visible when the control center is opened) changes from “Verizon” to “VZW Wi-Fi” as a reminder that your voice calls and SMS texts will be delivered via your Wi-Fi Internet connection. I assume something similar happens with other carriers.
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Strange. Must be T-Mobile. For me, if I turn it on it is on whenever there’s a Wi-Fi connection with sufficient bandwidth, whether or not there’s a good cellular connection.
This has been happening to me with AT&T since the beginning of the year. Only, in my case, the provider repeatedly drops the call, unable to decide whether to use WiFi or cellular.
Typically, during a call over WiFi, the connection is simply dropped. This never happens over cellular. It appears that AT&T, if it has any problem with WiFi, does not switch to cellular; it just ends the call.
This never happened before this year. AT&T support maintains it is not their problem.
Just to add another anecdotal data point, I’m at home on Verizon with WiFi calling turned on and with an excellent cellular signal (from my Verizon network extender) and my phone is not on VZW-WiFi as long as the cellular connection is good. The network extender’s range is not great, and our phones will switch to WiFi calling when it gets to about 2 bars.
That said, when the cellular connection is not good, WiFi calling is rock-solid for both my phone and my wife’s phone, and that goes especially when we travel internationally.
I just checked, and that’s what my phone shows right now (at home).
And 2 bars is what my phone is showing.
This topic is interesting to me for a somewhat different reason. I have limited data on my phone’s plan, so I would rather not use cellular data when Wi-Fi is available. I understand FaceTime video uses data rather than minutes (which are unlimited on my plan), and I prefer FaceTime video for some of my calls. (Also, like @tidbits22, I’m not interested in changing settings depending on my environment.)
Does that generalize? If Wi-Fi is connected, does the phone use Wi-Fi for data even if there is a good cell signal? I hope so, but have not tried to investigate.
Yes, unless you have enabled Wi-Fi Assist, in which case, the phone may use some cellular data along with Wi-Fi data, if it detects problems with the Wi-Fi.
This is a good feature if you have an unlimited data plan, but could be a problem if you have a metered plan or are roaming. So it’s good that you can choose to enable or disable it.
Thank you. (Pats self on back.) I disabled Wi-Fi Assist because that was my reading of the situation.
Wi-Fi calling is for calls and non-iMessage text messages only. The only time mobile data is used is when you have Settings / Cellular / WiFi Assist turned on and you have a poor WiFi signal; then the phone may use cellular data. Keep that option off and your phone will always use WiFi when it’s connected.
Well, for Verizon there is another option to check if you have 5G. Settings / Cellular / [tap your SIM - probably “Primary” if you have an eSIM only phone] / Data Mode. You probably want “allow more data on 5G” turned off if you want to limit data usage. I have it off myself, but I have unlimited data, so it’s not a worry for me if it’s on.
I managed to develop that habit. I live in a place where the only cellular signal bounces between zero and one, and I don’t have a landline. So now I’m in airplane mode with Wi-Fi on whenever I’m home. When I make forays to town for supplies, I take it out of airplane mode.
Long ago I read it takes 30 days to develop a habit :)
I was with AT&T Prepaid all last year. I had to do the manual turn off cellular, let AT&T WiFi come up, then turn cellular back on. It didn’t always hold. This year, I switched back to US Mobile. On the Verizon (Warp) service, it almost always goes to WiFi Calling at home. But, thought I’d see what US Mobile’s AT&T service would do and just like AT&T, I had to switch manually. Switched back to Warp and it always comes up on WiFi Calling at home. Weird.
I’ve had a similar experience. Verizon seems to switch readily to wifi calling as soon as the wifi signal is halfway decent. T-Mobile on the other hand could be quite stubborn in resisting to switch over.
I know there must be some other “hidden” requirements as to ports or something else because I know there are certain labs on campus here where I can never get an iPhone to switch to wifi calling even though wifi is strong and wireless b/w is high with low latency. Some of those switches are configured in a quite restrictive manner (lots of specific ACLs) so I always wonder what it is exactly that prevents wifi calling for working on an otherwise excellent wireless connection.
Yeah, it’s a messed up circumstance. AT&T is actually better in my area of Dallas than Verizon, but not switching to WiFi calling was a deal breaker for me.
In the iOS setting named Wi-Fi Assist, the description reads:
Automatically use cellular data when Wi-Fi connectivity is poor.
Could this sometimes interrupt voice calls while Wi-Fi Calling is ON?
My feeling is that WiFi calling would not be active if the WiFi signal is so poor that WiFi assist would switch data connectivity to cellular.
I seem to remember (sorry, no opportunity to research links right now) Verizon checking to make sure the Wi-Fi connection is good enough to provide a voice call experience that is up to their normal mobile calling standards. This means high-enough bandwidth and low-enough latency. I presume that this means that when you enable the feature, the phone is periodically sending probe packets to their voice server pool in order to check those parameters.
Even if your local Wi-Fi and routers are providing lots of bandwidth and low latency, that doesn’t necessarily mean that those conditions hold true for connections to the VZW voice servers.