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PSA: Keep an eye on your mobile data if you ever use poor-quality WiFi


If you ever use your iPhone on poor-quality WiFi networks, you may want to check your mobile data usage. As Quartz noted, a new feature introduced with iOS 9 is leading some people to see dramatic increases in their mobile data usage.

Wi-Fi Assist means that iOS recognizes slow WiFi and supplements it with mobile data. Great for ensuring your browsing experience doesn’t suffer, but it can come at a cost, with some users reporting that their iPhone is now using literally gigabytes more mobile data since upgrading. Unless you have unlimited data, that can get expensive.

Wi-Fi Assist is on by default, and rather hidden away in Settings, so here’s how to switch it off … 

You can switch it off in Settings > Mobile Data (or, on Verizon phones, Settings > Cellular > WiFi Assist) – but you could be forgiven for not noticing it, because unlike other system-wide toggles which appear at the top of the screen, Wi-Fi Assist is tucked away at the bottom, underneath all the app-specific toggles.


This settings screen is also where you can check out your mobile data usage.

Apple reported a week ago that iOS 9 has experienced the fastest adoption rate of any version of its mobile operating system. If you still haven’t had time to explore it fully, check out our walk-through of the new features.

Via Business Insider

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  1. Stetch´s Photo - 7 years ago

    Yeah .. I have 12GB surf every month. I rarely go over 5Gb but this time all the 12Gb went away :/ So this function will be deactivated.

    • srgmac - 7 years ago

      Damn…how much does that cost? I still have the 30$ unlimited plan from Verizon…I have to pay full price every time I want a new phone but it’s so worth it; some months when I travel I download at least 100-200 GB…they would probably charge me an arm and a leg for that!

  2. nana (@purplemaize) - 7 years ago

    With my plan I get 6GB for 2 of my phones, I do a lot of beta testing and download plenty on Wi-Fi assist, has not affected me at all, my phone bill has been the same.

    • fistsoffrost123 - 7 years ago

      Jeez, turn it off to be precautionary. I can’t believe someone at Apple thought it would be a good idea to turn this on by default.

  3. Graham Brotherton - 7 years ago

    This was NOT enabled by default on my phone, I went in and enabled it

  4. Randy Isdahl (@epee4fun) - 7 years ago

    On my iphone 6 (Verizon) the switch was under Settings-Cellular-WiFi Assist. It was at the bottom of the screen as the writer stated.

    • Robert F Corbin - 7 years ago

      Thank you! I originally couldn’t find it to turn it off…

    • gkbrown - 7 years ago

      Same here (T-Mobile).

    • 89p13 - 7 years ago


      I thought it had been removed in the Developer 9.1 Beta – but then I saw your post and it’s still there and was still enabled!

      Thank you

    • jamessmooth - 7 years ago

      Thank you! I was going crazy trying to find it. For once, Lovejoy confused me. :)

  5. jxslepton - 7 years ago

    att grandfathered unlimited data plan ftw

  6. modeyabsolom - 7 years ago

    A useful tip – thanks.

  7. proudinfidelusmc - 7 years ago

    T-Mobile Unlimited Data FTW!


Avatar for Ben Lovejoy Ben Lovejoy

Ben Lovejoy is a British technology writer and EU Editor for 9to5Mac. He’s known for his op-eds and diary pieces, exploring his experience of Apple products over time, for a more rounded review. He also writes fiction, with two technothriller novels, a couple of SF shorts and a rom-com!

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