Can AT&T really add a pricey data plan onto your wireless bill?

If you're an AT&T Wireless customer, you might not have a data plan today. And if you want to keep things that way, I suggest you avoid playing around with new phones using your existing SIM card. Based on some odd messages and a lengthy AT&T Customer Care session this morning, I predict that some Windows Phone users are about to get a shock. It's all part of the mobile carriers' plan to ratchet up their profits by jacking up your monthly bill, a business model that is key to their continued growth, as I explained last week.

The good news is that switching from an iPhone to a Windows Phone should have no effect on your existing data plan. With thousands of Microsoft employees about to get their new, free Windows Phone devices, there are plenty of people in that category.

A little background: AT&T requires you to have a data plan if you activate or upgrade to a smartphone. That policy has been in effect since September 6, 2009. In June of this year, the company revamped its data plan pricing, eliminating unlimited data plans for new customers. Longtime customers like me, who previously had unlimited data plans with an iPhone or another smartphone, can keep the unlimited plan as long as they remain customers but lose the option completely if they switch to a lower-priced usage-limited plan.

As more people switch from feature phones to connected devices, they're about to see a big increase in their monthly bill, sometimes without their own knowledge. As soon as they start using data, AT&T will sign them up for a monthly data plan, automatically.

I got a preview of what those users will see, very early this morning. Sometime after my first cup of coffee but before I was fully awake, my phone chirped to let me know I had just received a text message. It was from AT&T, it assured me it was free, and it was very odd. Here's the full text:

Did you know a data plan is required for your Smartphone? We have added an appropriate data & msging plan. Learn more @ att.com/smartphoneplans. [emphasis added]

When I saw that tweet, I thought back to several casual conversations I had with Microsoft employees last week about the new Windows Phone devices they're about to receive. At least one was concerned that he was going to lose his unlimited iPhone data plan when he switched.

About 10 seconds after I had that thought, an e-mail message popped into my inbox. It was from AT&T Customer Care for Wireless. Here's what it read:

Dear Valued Customer,

We hope you are enjoying your Smartphone! We appreciate and value your business and want to be sure you are aware of a change we've made to your account to ensure you have the best possible experience with data on your Smartphone.

Smartphones are made for data consumption-surfing the web, social networking, email and more. That's why we require an eligible Smartphone data plan in conjunction with our Smartphones. This ensures that customers with data intensive devices are not unpleasantly surprised with high data pay-per-use charges.

For whatever reason, our records indicate your Smartphone does not have an eligible data plan. We have added an appropriate Smartphone data plan for your device. We've also added a messaging package to match the messaging plan included in your previous data and messaging bundle. [emphasis added]

If you would like to select another Smartphone plan or messaging plan or have questions, please call 1-800-331-0500 (or 611 from your wireless phone) or visit att.com/smartphoneplans.

Thank you for being an AT&T customer. We look forward to continuing to provide you with a great Smartphone experience.

Sincerely,

AT&T

My wife, I discovered later, got the same text message. Now, this is completely baffling in our case. We have been AT&T Wireless customers since back when they were Cingular. It might not be quite a full decade, but it's close. We have had wireless data plans for our AT&T/Cingular accounts for about as long as they have been offered. Despite the truly crappy signal coverage in our home and my office, we have remained AT&T Wireless customers for the more than five years we have lived in our current home, locked in first by contracts with early termination fees and then, more recently by my wife's sheer love of her iPhone and the lack of a suitable alternative device from Verizon.

The point is, I shouldn't have gotten this message at all. And after more than an hour of digging through the tremendously confusing AT&T Billing site and speaking with a senior Customer Care agent I determined that nothing in our already overpriced account had been changed.

So why did I get that message? Because I recently moved my SIM card to a new device, the HTC Surround running Windows Phone 7 that I wrote about last week. I've done that at least five times this year as I switched between smart devices on the AT&T network: an iPhone, a couple of Windows Mobile devices, and two Windows Phone 7 devices. (My unsatisfying experiment with a Droid was on Verizon.) As the Customer Care representative explained, AT&T these days is paying much more attention to the devices that connect to is network than before. He assured me that I would get that same inaccurate sequence of messages again if I moved the SIM card to another device. If I had been on a no-data plan, my rates would have gone up substantially and immediately.

I confirmed that the official policy allows you to keep an existing unlimited data plan even if you switch smartphones. In my case, I have the original $20 iPhone data plan (that same data plan is now $10 a month more). I was assured that my data charges will not change when I replace my iPhone with a new device.

The customer service representative made it very clear that he was not describing AT&T policy but rather "looking at the details of my account to see what was going on." But the implication was equally clear: if you play around with a new integrated device (aka Smartphone), AT&T is watching.

Update 17-Nov: In the Talkback section, commenter Day2die confirms that trying to use an unsubsidized smartphone without a data plan (for example, buying a secondhand iPhone and using Wi-Fi for apps and phone for voice only) simply is not allowed by AT&T:

I can assure you that this has happened to me. I bought my iPhone 3G unsubsidized and has been using it on AT&T's network wthout a data plan since 2008. Earlier this year, I got the same message from AT&T saying that it added a data plan to my bill. I canceled the data but was dismayed that AT&T added the data plan back on the following day. AT&T told me that there is no way I would be able to get away with using a smartphone without a data plan since it uses IMEI to track my smartphone usage.

I have strong Wi-Fi in most places and do not need a data plan. I am currently stucked using a feature phone. So my question to you, Ed, is that is there any carrier or anyway for me to buy a smartphone unsubsidized and use it without a data plan?

If anyone at AT&T wants to respond, on or off the record, please get in touch.