AT&T has begun throttling bandwidth speeds for its "unlimited" wireless data customers who gobble excessive amounts of data on their smartphones - just as it promised it would back in June. Now that the unlimited wireless bandwidth party is over, some AT&T customers are not happy, speaking up, and crying foul.

Despite AT&T's assertion that throttling will only affect a tiny top five percent of data users some customers claim the clampdown on wireless bandwidth appears to be impacting a larger portion of AT&T's 17 million wireless customer base. Of those believed throttled, some claim AT&T bandwidth restrictions are worse than other carriers' that already throttling wireless bandwidth hogs. They also complain AT&T isn't being clear about its throttling policy and that they are getting hosed by a new pricing scheme.

AT&T isn't unique when it comes to moving away from all-you-can-eat data plans and pushing customers toward tiered service plans. Verizon, T-Mobile, and others in the wireless industry have ditched unlimited plans as well. They have also faced customer backlashes.

AT&T Undocumented Limits

For the record, AT&T has stated in the media if you use more than 2GB of wireless data a month you are part of the five percent of its customers who could be subject to throttling. An AT&T representative confirmed the limit but says exceeding 2GB of data is no guarantee you'll be throttled. AT&T told The New York Times actual slowing of wireless data speeds is dependent on individuals and their usage patterns and the immediate availability of network capacity or spectrum.

Unfortunately, AT&T does not make the above clear on its site leaving many in the dark. We did find a footnote to the old Unlimited plan on the AT&T site but it directed us to new data plans instead of a new policy. When we called customer support an AT&T spokesperson said she didn't have any information about what new limits the Unlimited plan and directed us back to the AT&T site.

By comparison Verizon offers guidance of its throttling policy as do wireless carriers such as T-Mobile.

Pricing Conundrum

AT&T's existing Unlimited customers are grandfathered into their $30-a-month Unlimited plan and limited (theoretically) to 2GB of wireless data transfers. After that speeds are significantly reduced, according to user feedback.

Separately, AT&T offers a $30-a-month plan for 3GB of data downloads. That has some griping: "that's one gigabyte more than the 'unlimited plan' allows before AT&T considers you among the top five percent of its 'heavy users' subject to a punishing speed throttle."

No way around it, it doesn't seem fair to charge two groups of users the same amount for two different data caps (even if one isn't technically a cap). The only silver lining might be is that Unlimited customers won't face nasty surprise "overage fees".

Unfair Throttling

If pricing and policy issues weren't enough, now a growing chorus of AT&T customers insist they are seeing data throttling before they hit a 2GB limit. AT&T customers have been chiming in at popular blogs such as John Cozen's and the site Cult of Mac. Commenters at both sites insist they are seeing throttling of their AT&T wireless speeds after as little as 1.5GB of data consumption.

Of course, without independently verifying the above claims it could be a case of sour grapes.

Last Holdout

Lastly, not all phone carriers limit user data. Sprint famously allows unlimited data without restrictions. Yes, it is pretty much fourth among the big four carriers, but it still makes AT&T, T-Mobile, and Verizon seem like cheapskates.

(PCWorld's Tom Spring contributed to this report)