Eek! It looks like AT&T is hunting down MyWi users in attempt to put an end to grey-market tethering. Many customers have received an email (or text) from AT&T asking them to upgrade to a paid tethering plan in order to retain the ability to use their device as a mobile hotspot. We’re not sure how serious AT&T is, or if they know for sure that these users are tethering illegitimately—and not just using tons of bandwidth—but it couldn’t hurt to call AT&T to make sure you don’t rack up any unexpected charges.
Reddit user byu146 explains that it is very possible for AT&T to pin point MyWi users, since all network traffic has a TTL, or “Time To Live”, which is different for mobile devices and laptops.
The thing is, ALL routing devices do this. OSes use standard TTLs. For example, let’s say both your iPhone and laptop use 127 for the TTL. AT&T will receive packets from your iPhone with a TTL of 127, but since the packets from your laptop pass through your iPhone first, they arrive at AT&T with a TTL of 126. They can detect a tethered device this way.
Changing a device’s TTL is technically possible, and if the problem with AT&T continues, a workaround to fool AT&T may soon pop up in Cydia. (Spoofing your user agent will not help!)
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 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:
Data Pro 4GB for Smartphone Tethering
- $45 per month