According to CNN Money many iPhone users have complained about unusually high cell phone bills after upgrading to iOS 9. Wi-Fi Assist is most likely the culprit.
Wi-Fi Assist is a new feature in iOS 9 that toggles your iPhone over to cellular data if you are connected to Wi-Fi and have a weak signal. Chris Mills from Gizmodo shared his experience with Wi-Fi Assist and noticed that his cellular data usage increased from his normal 3GB to 4GB a month.
Apple has enabled the feature by default so if you are on a limited data plan you may want to go ahead and switch Wi-Fi Assist off. To do so..
1. First open the Settings app.
2. Choose the Cellular Data option.
If you are on an unlimited data plan, Wi-Fi Assist is a useful feature. The seamless transition between Wi-Fi and cellular comes in useful when you either leave a Wi-Fi area and move to cellular or if you just have a poor Wi-Fi connection.
In the past I bet that you’ve had a text message fail to send or a podcast cutout for half a block as you left your house to walk your dog. Prior to iOS 9 your iPhone would hold on to that weakening Wi-Fi signal even when it became useless and there was an aggravating lag before it transitioned to cellular data. There were also those situations when you turned off Wi-Fi because of a bad connection only to forget to turn it back on. With iOS 9, Wi-Fi Assist solves those problems.
If you are on a limited data plan, you can still enjoy the usefulness of the feature as long as you monitor your data usage and know how to tell when Wi-Fi Assist has made the switch over to your cellular data. Your iPhone will not notify you when it transitions, but there is one small clue to look for. The Wi-Fi icon at the top of the screen will become grayed out when switched to cellular. When you notice the gray Wi-Fi icon you should probably quit streaming Big Bang Theory and try to find a better Wi-Fi connection.
All four of the major carriers have iPhone apps that will help you monitor your data usage. So if you plan to use the feature and you are on a limited data plan I would suggest downloading and setting up one of these apps if you haven’t already.
When Apple introduces a new useful feature there’s always the risk of negative side effects. Wi-Fi Assist is a helpful addition to iOS but it comes at a price. Maybe a big price if you aren’t careful. If you choose to use the feature be sure to monitor your data and look for the grayed out Wi-Fi icon. Also, if you are streaming content, such as a podcast or a ballgame, be aware of when you leave a Wi-Fi connection.