The Kindle 3G models are not limited to using Amazon's 3G M2M plan (M2M == Machine to Machine).
Paraphrasing from the AT&T FAQ "How do I buy a DataConnect Pass" ::
You will need :
* A device which is DataConnect Pass capable with an unactivated AT&T SIM card.
- You can buy an unactivated AT&T SIM card from Amazon for $2.35
* An AT&T-certified laptop, netbook, PC card, or tablet
- The AnyData, mini-PCIe card (DTP-600W) has AT&T "Carrier type approval".
= ref:
https://att.m2m.com/devkit/# click the "see list" link in second line of footer.
* On-line access (your reading this, you must have that).
* Credit card/debit card, PIN or Refill Card
Got all of that? Now, put
your new SIM card in your Kindle
The cover slide is marked, showing which direction to slide it to unlock, then the cover swings up, take out Amazon SIM, put in your SIM.
While you have your Kindle open, make a note of the IMEI number on the 3G card's cover.
The ICCID is on both the SIM you just installed and on the long label of its carrier card it came on.
Go to this site:
https://buyasession.att.com/sbd/Cust...uctInfo.action
Note 1: When picking your plan - you need to pick one that allows tethering if that is what you intend to do (use your Kindle as a 3G gateway for your non-3G devices).
Note 2: I have not (yet) done this myself, but I can not see why it shouldn't all "just work".
So any reports of success/failure from people who try this would be good to post here.