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.

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.

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.