A new change for AT&T Wireless’ Unlimited Data subscribers will soon be taking place. Rumored to be starting in the first week of October, we’ve heard that AT&T will start throttling the data speeds of the network’s top data hogs.  As Verizon (PDF) and Virgin have recently done, AT&T will be adopting a similar plan to try to curb the problem of data congestion and overall network issues that have hurt its 3G network’s performance since the onset of the iPhone.

AT&T will also be releasing its first LTE devices later this year.

We’ve heard that AT&T will rejigger its insurance structure that week as well, which makes us think a certain high profile device may be launching on or around that time.

The throttling plan will work like the others’. The heaviest users will see significant speed decreases for one billing cycle once they go over a threshold of data (we’re guessing 2-4GB?).  These heavy users will still be able to access the network, but at a much slower speed.  At the start of the next billing cycle, their speeds will return to normal.  We don’t have numbers for AT&T’s throttle speeds but Virgin takes you down to 256Kb/s once you’ve reached their 2.5GB limit (not too bad actually – sometimes we’re happy to get 256kbs).  Interestingly, Virgin’s throttle also will also be implemented in the first week of October which may indicate that they’ll be carrying a certain high profile mobile device as well.