Last Updated: Aug. 4, 2014

Question: Can I Keep Unlimited Data with iPhone Tethering?

I'm excited that AT&T has allowed iPhone tethering (finally!), but I know they also recently changed their data plans. I've got the unlimited iPhone data plan that came with the original iPhone, which seems perfect for tethering, but can I keep the unlimited plan if I want to get tethering?

Answer:

An unlimited data plan would be the perfect match for the iPhone's Personal Hotspot feature, wouldn't it?

While it's perfect from the user's perspective, it's not AT&T's version of a perfect world. That's why, when they changed their data plans, they set terms for tethering.

Tethering cannot be used with an unlimited iPhone data plan from AT&T. Instead, using tethering requires that you have AT&T's 5GB data plan or higher, which currently costs $50/month (any data plan above 5GB also includes tethering). Unlike in the past, though, there are no additional charges for tethering. If you use more than 5GB of total data in a month, overages run $10 for 1GB. 

All cellular data—whether on the phone or via Personal Hotspot—combines to count against your monthly allotment. For users who don't tether, this should be OK, but with tethering, you may need to keep an eye on your monthly data use.

UPDATE March 2014

While this article was originally specifically about AT&T's data plans, it applies to virtually all carriers in one form or another. No carrier that I'm aware of offers unlimited data for Personal Hotspot at the highest speed any more (AT&T and Verizon both offered unlimited data in the early days selling the iPhone, but that changed as it became clear that that option was financially untenable for them), but they all include it at no extra cost in one plan or another.

Some carriers charge for overages, while others throttle your speed—i.e., reduce the speed of the connection after a certain amount of data used each month. But either way, there will be some limits based on your use.