WP7 “Phantom Data” Source Possibly Revealed?

Recently there’s been rumours floating around regarding “phantom” Windows Phone 7 data being magically sent and received on the latest WP7 phones. The news has mostly been floating around twitter so I didn’t pay it much attention. The BBC Technology News picked it up so I thought I would look more into it myself seeing that we have WP7 phones and maybe there was some truth to all this (and more importantly what was the cause).

Full disclosure. I don’t have a lot of data points around this. This is from looking at a few phone logs, changing the configuration and looking back again after the change. I haven’t done a clean baseline test nor have I done testing with hundreds of phones. I leave the experience up to the reader to decide.

So I went spelunking into the phone logs to see what was up. Most providers will show you data usage, at least on a daily basis. I lucked out with the provider and plan in that they provide hourly breakdowns. Here’s a snapshot from my usage throughout one night.

Timestamp Data Usage
12:38:30 AM 2098 Kilobytes
1:30:30 AM 2 Kilobytes
2:38:30 AM 7118 Kilobytes
3:38:30 AM 6622 Kilobytes
4:38:30 AM 76 Kilobytes
5:38:30 AM 29 Kilobytes
6:38:30 AM 19 Kilobytes
7:38:30 AM 20 Kilobytes

So a few observations from this data:

  • Data seems to be collected on a regular basis. Looking at some other people phone logs, the times vary but it’s always hourly.
  • There’s not a tremendous amount of data here (about 16 megabytes) but it seems like a lot for 7 hours
  • The phone was connected to my home Wifi during this period
  • Nothing was running and the phone was in a locked state

Like I said, not a lot of data but it adds up. 16MB for 7 hours = about 50MB in a 24 hour period. That’s just plain old data being collected (somewhere, somehow) and not actual usage (Marketplace, Email, Browsing, etc.). Besides, when connected to a WiFi network you shouldn’t be charged data usage from your phone company (in theory, YMMV).

After reviewing the logs I made a theory that the only thing that could possibly be sending data is the Feedback feature. With no other apps running under lock, what else could it be?

In Windows 7 under your Settings the last option is Feedback. This sends feedback to Microsoft to “help improve Windows Phone”. On this page you have three options:

  • Send feedback and use my cellular data connection
  • Send feedback and (presumably) use my WiFi connection
  • Don’t send feedback

Knowing what I know about Microsoft, they do use the feedback data. For example some of the placement and inclusion of features in Office 2007 was based on that Feedback data that Office sends (assuming you had opted in).

However in the Privacy Statement (it’s long but a good read at least once in your life), the Phone manual, and every other source I could look at there is no information about how much data it’s planning to send, just that it’s sending some data and that “some data charges with your carrier may apply”.

Looking back at the logs, I have to wonder. 6MB at 3:30 and *then* 7MB the next hour. That’s a lot of information. And it adds up. 50MB in a 24 hour period X 30 days puts most people over a normal 1GB plan. And frankly why am I paying for a data plan only to have 80% of it chewed up by Microsoft, with no real benefit to me. If they included porn in the 50mb daily transfer I’d be okay with this, but I don’t see any new movies on my phone.

So I turned it off. Set Feedback to disabled and wait.

I waited. And waited. And generally didn’t use the phone if I could.

The next day I went back to look at the data usage logs from the time period after turning the feedback mechanism off. Here are the results.

Timestamp Data Usage
1:19:48 PM 0 Kilobytes
2:19:48 PM 0 Kilobytes
3:19:48 PM 0 Kilobytes
4:19:48 PM 678 Kilobytes (took a phone call)
5:19:48 PM 82 Kilobytes
6:19:48 PM 88 Kilobytes
7:20:30 PM 86 Kilobytes (guess they changed their reporting time)
8:20:30 PM 86 Kilobytes
9:20:30 PM 66 Kilobytes
10:20:30 PM 67 Kilobytes
11:20:30 PM 49 Kilobytes
12:20:30 AM 32 Kilobytes
1:20:30 AM 38 Kilobytes
2:20:31 AM 18 Kilobytes
3:20:31 AM 27 Kilobytes
4:20:31 AM 86 Kilobytes
5:20:31 AM 53 Kilobytes
6:20:31 AM 22 Kilobytes
7:22:15 AM 30 Kilobytes (another reporting time change)
8:22:15 AM 29 Kilobytes
9:22:15 AM 74 Kilobytes
10:22:15 AM 154 Kilobytes (phone call)
11:22:15 AM 12 Kilobytes
12:13:27 PM 49 Kilobytes
1:13:27 PM 197 Kilobytes (phone call)

Quite a *drastic* change from what Feedback was turned on. I mean for a 24 hour period (sans 3 phone calls) I consumed about 1MB. Still quite a bit of transfer going on but at least it amounts to 30MB per month, not 30MB per day!

Like I said this observation is neither scientific or conclusive. You decide what to do but frankly until Microsoft makes this data transfer exempt from your data plan (like that will happen) I would just turn Feedback off. YMMV.


  • Argh! I know it helps to improve the experience, but not when it costs me money!

    I used to never send the "an error has occured. Do you want to send this to Microsoft?" dialog boxes, but since I found out that they actually do fix problems based on those, I'll send them the errors I get.

    Maybe I'll remember to turn on the feedback during the last week of a month or something

    Good sleuthing!

  • I have also turned on feedback, even over my mobile connection, and I can't confirm that behaviour. I have a total traffic of about 60 MB from my 3 GB package since January 1st and use data services very often, so this is a absolutely normal traffic amount.

    So it seems that feedback could be the cause, but it's rather caused by a bug that affects only a few scenarios/devices and is not a general problem.

    Thanks for sharing, very intresting!

  • This is an AT&T problem in my opinion. iPhone 3G S also has /had the same problem nov/Dec 2010. I complained to at&t but did not follow up because I have unlimited data plan. However, my Wife's wp7 reported over the limit data usage barely 7 days after activation this month January 2011. This wp7 is always within wifi range except when she goes to pick kids from school or trip to grocery store. These two outings do grant enough time for active data usage. So I still believe AT&T has not explained problem. My wife's overage charge was refunded. I will demand same for the current billing cycle.

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