Think twice before tethering that iPhone

AT&T won't let you tether your iPhone to a PC for on-the-go broadband until later this summer, yet a series of do-it-yourself tutorials have already sprung up on the Web. But before you go downloading HD movies over your makeshift tethered iPhone connection, take heed.

Of course, the ability to share your iPhone's data connection with your PC over USB or Bluetooth is one of the most-anticipated features of iPhone Software 3.0, but AT&T has (infamously) announced that it won't have an official tethering plan until later this summer.

Meanwhile, iPhone Software 3.0 arrived only yesterday—an eternity in the blogosphere, of course, leaving enterprising hackers plenty of time to develop a simple download that'll enable PC tethering on your iPhone without AT&T's help (or permission).

Pretty cool, right? But here's the thing: If you do go ahead and enable the tethering hack, you'll still be using AT&T's wireless data network, and—right or wrong—you'll be violating AT&T's "terms of service."

Here's the relevant passage from the AT&T wireless service agreement:

Furthermore, plans(unless specifically designated for tethering usage) cannot be used for any applications that tether the device (through use of, including without limitation, connection kits, other phone/PDA-to computer accessories, BLUETOOTH® or any other wireless technology) to Personal Computers (including without limitation, laptops), or other equipment for any purpose.

OK, so what if you go ahead and tether anyway? (And trust me, if you download the HD version of "Wall-E" over your tethered iPhone, AT&T's going to notice.) Well…

Accordingly, AT&T reserves the right to (i) deny, disconnect, modify and/or terminate Service, without notice, to anyone it believes is using the Service in any manner prohibited or whose usage adversely impacts its wireless network or service levels or hinders access to its wireless network, including without limitation, after a significant period of inactivity or after sessions of excessive usage and (ii) otherwise protect its wireless network from harm, compromised capacity or degradation in performance, which may impact legitimate data flows.

In other words, AT&T is claiming the right to cut off or otherwise "modify" (which could mean exorbitant data charges, akin to roaming charges) your service if you attempt any unauthorized tethering.

Is that fair? Well, fair or not, if you have an iPhone on AT&T and you signed a service contract, you've agreed to the terms of service. Something to ponder before you go a-tethering.

Meanwhile, the Unofficial Apple Weblog has the AT&T tethering rumor du jour: That the carrier will have a tethering plan ready by "mid-July," and that the plan will cost a "whopping" $55 a month.

It's not clear, though, whether that means $55 on top of the iPhone's $30/month data plan or $55 all told. AT&T already has a "PDA Personal with tethering" plan for $60 a month that includes smartphone data and tethering, so I'd hope that iPhone users will get something along those lines once AT&T goes public with the details.

Related:
AT&T iPhone customers: tethering is coming, for a price [TUAW]