This is interesting, ,don't know if it's been reported before but while playing around yesterday I decided to see if the active SIM in my 2G iphone would work in my 3GS. I plugged it in, played for a couple of minutes and then switched back to the real 3GS SIM.

I found this in my mailbox this morning:

Our service records indicate that you are using an iPhone 3G with a data plan designed for other devices.

To avoid unexpected data overage charges and enable Visual Voicemail, please contact your telecom manager, or an AT&T representative at 1-800-331-0500.

Thank you for choosing wireless from AT&T. We appreciate your business.

Sincerely,
AT&T Customer Service

Originally Posted by unclemiltie

This is interesting, ,don't know if it's been reported before but while playing around yesterday I decided to see if the active SIM in my 2G iphone would work in my 3GS. I plugged it in, played for a couple of minutes and then switched back to the real 3GS SIM.

I found this in my mailbox this morning:

Our service records indicate that you are using an iPhone 3G with a data plan designed for other devices.

To avoid unexpected data overage charges and enable Visual Voicemail, please contact your telecom manager, or an AT&T representative at 1-800-331-0500.

Thank you for choosing wireless from AT&T. We appreciate your business.

The 2G has a very different revenue split deal between carriers and Apple, this means AT&T needs to be more strict about which plans and SIM cards you can use with the 2G.

What's interesting is that when I put the 2G SIM in the 3GS, ATT nearly immediately sent me a text and email that I was using the 2G plan with the 3G network. (i.e the plan that I pay $20 for in the phone that needs a $30 plan)

When I put the 3GS SIM into the 2G while I was jailbreaking/restoring/etc the 3GS ATT didn't seem to notice or care.


It's good to know, however, that if/when something happens to the 3GS I can use the 2G as a backup.

-bill