AT&T iPhone tethering to cost $20 a month extra, requires you to ditch your unlimited data plan

Gather round, everyone! It’s time for this week’s edition of “Good news, bad news” — only this week, “bad news” is being supplanted by “terrible news”.

The good news: As we touched upon earlier, AT&T has finally confirmed that iPhone tethering will launch this summer.

The bad terrible news: You’d have to be pretty crazy to bother with it.

Here’s how the new set up works:

  • First, you’ve gotta be signed up for AT&T’s $25 DataPro plan, with its cap of 2GB per month. Already on AT&T’s now retired $30 unlimited data plan? Bummer, dude – no tethering for you. Unless you downgrade to the 2GB-per-month plan, thereby forever killing your access to the unlimited plan.
  • Once you’re on DataPro, adding tethering support to your plan will set you back an additional $20 per month. That brings the total cost of your data plan up to $45 a month.
  • Note that that extra $20 a month only adds tethering — you don’t get any extra bandwidth.

As AT&T points out: before (AT&T-supported) tethering is factored in, less than 2% of people actually manage to go over 2 gigs — and, in some sense, those that do are the ones bogging down the network the most. Squeeze them out (or at least mellow their downloading habits), and the network speeds up for everyone else.

And back to the downside: Good luck staying under 2 gigabytes a month if the rumors like 3G video calling and iTunes streaming pan out.

Your thoughts? Let us know in the comments.