It seems there’s a relatively serious bug appearing with Windows Phone 7: sometimes it’ll use 3G data even when a Wi-Fi network is available. Over at WinSuperSite, a reader emailed WP7 guru Paul Thurrott, and asked about why her phone was mysteriously and constantly sending data, causing her to go over the plan’s limit. Thurrott responds:
Yes, this is a curiously common problem, and I’m sort of shocked Microsoft hasn’t addressed this publicly yet, either to confirm it or to offer a fix. Basically what’s happening is that the phone is utilizing the 3G data connection even when Wi-Fi is available. It’s not clear what app(s) or part(s) of the OS is causing this, but it’s definitely widely-reported.
He’s not the only one to comment on this. One of the guys behind ChevronWP7 posted this on his blog:
When you’re downloading apps from the Marketplace there is a 20MB limit by default over 2/3G. This limit is imposed by the phone and cannot be changed…
Now, there is a “bug” in the marketplace downloader on the phone, which, if you’re connected to a WiFi network that doesn’t have an internet connection, it will default back to your 2/3G connection and download said app.
I have a sneaking suspicion that there are actually two problems at work here. One is the cited issue of the phone switching over to 3G when it doesn’t need to, but there’s also a deeper problem at work. If you look at our sister iOS site EverythingiCafe, two incredibly vibrant discussions (here and here) have arisen about people having huge blocks of data transmitted to AT&T in the dead of the night — and not just iPhone users, but also a bunch of Android owners too. I have a sneaking suspicion that this plays a role in the problems too.