Windows Phone 7 users beware - you could be approaching your 3G data allowance limit without excessive browsing and without even realising it.

Web forums are alight with talk of phantom data being used, even when the phone is idle.

A Windows Phone 7 user wrote into Paul Thurrott's Supersite for Windows stating that he had received a letter from his network saying he was close to exceeding his 2GB allowance. Upon checking he noticed that random data was being sent without him knowing:

"For instance on November 21-24 it sent between 30 and 50 MB of data at 10:41pm each day and Dec 1-4 it sent between 30 and 50 MB of data at 9:41am each day.  On December 23rd I turned on airplane mode so my phone could no longer send data.  I turned airplane mode off briefly on December 23rd and the phone sent 400 MB of data."

Thurrott replied that he was shocked that Microsoft was yet to publicly acknowledge what is apparently a widespread problem.

Other posts on WP7 forums have claimed that up to 1GB of data has been used, even when a phone is just left alone without being used and in an area where it should be picking up Wi-Fi anyway.

With all of the UK networks now applying a data cap on mobile contracts, and pretty hefty fees if you go over, this is a very serious problem and we expect that Microsoft may have something to say on the matter soon.

Let us know, using the comments function below, if you are a WP7 user affected by this issue.