AT&T has started to issue warnings to customers unofficially tethering their smartphones to its network. In an email to unauthorized tetherers, the company writes, “Our records show that you use this capability, but are not subscribed to our tethering plan.” The correspondence goes on to note that users will be automatically enrolled in the $45 per month “DataPro for Smartphone Tethering” plan if they ignore the warning. “The new plan – whether you sign up on your own or we automatically enroll you – will replace your current smartphone data plan, including if you are on an unlimited data plan,” the email continues. The standard DataPro offering is $25 per month and provides users with 2GB of monthly data, although some users are still clinging to a discontinued, $30 per month 5GB data plan. It is safe to assume that a large portion of the unofficial, tethering populous is jailbroken iPhone users and rooted Android users. “If you discontinue tethering, no changes to your current plan will be required.” A copy of the email tethering-cheaters are receiving is after the break.

Dear [Name of Account Holder],

We’ve noticed your service plan may need updating.

Many AT&T customers use their smartphones as a broadband connection for other devices, like laptops, netbooks or other smartphones– a practice commonly known as tethering. Tethering can be an efficient way for our customers to enjoy the benefits of AT&T’s mobile broadband network and use more than one device to stay in touch with important people and information. To take advantage of this feature, we require that in addition to a data plan, you also have a tethering plan.

Our records show that you use this capability, but are not subscribed to our tethering plan.

If you would like to continue tethering, please log into your account online at http://www.wireless.att.com, or call us at 1-888-860-6789 Monday – Friday, 7 a.m. – 9 p.m. CST or Saturday, 8 a.m. – 7 p.m. CST, by March 27, 2011 to sign up for DataPro 4GB for Smartphone Tethering. Here are details on the plan:

DataPro 4GB for Smartphone Tethering

$45 per month (this gives you 4GB in total, combining both your smartphone data plan for $25 and the tethering feature, $20)

$10 per each additional GB thereafter, added automatically as needed

Mobile Hotspot capabilities are included for compatible Smartphones

If we don’t hear from you, we’ll plan to automatically enroll you into DataPro 4GB after March 27, 2011. The new plan – whether you sign up on your own or we automatically enroll you – will replace your current smartphone data plan, including if you are on an unlimited data plan.

If you discontinue tethering, no changes to your current plan will be required.

It’s easy to track your usage throughout the month so there are no bill surprises. For example, we send you free text messages when you reach 65, 90, and 100 percent of your plan’s threshold. If you would like to monitor your account more closely, go to http://www.att.com/dataplans to learn about other ways to track your data usage.

As a reminder, our smartphone data plans also include unlimited usage of Wi-Fi at no additional charge. AT&T smartphone customers can use Wi-Fi at home or on-the-go at any one of our more than 23,000 U.S. hotspots already included in your data plan.

Thank you for bringing your account up to date. We appreciate the opportunity to continue to serve your mobile broadband needs.

Sincerely,

AT&T