Alright, I did some swapping this morning, and below is what I have found out. In summary, the iPhone SIM, once activated seems to work fine in unlocked and newer and older AT&T/Cingular phones that are locked. Other AT&T/Cingular SIM cards will not work until activated with iPhone plans. They connect, can't dial. iTunes will let you activated it. Non AT&T/Cingular SIM cards will not work at all.

So, this phone has almost a double-lock on it. You have your standard GSM subsidy lock, but you also have some sort of mechanism that is tying the SIM card to the phone. This latter one I'm sure someone will figure out how to work around soon.

Phones:
iPhone (activated) 8gb Locked to AT&T/Cingular
Treo 680 GSM Unlocked & unbranded
SonyEricsson Z520 Locked to Cingular
SonyEricsson W600i Locked to Cingular

SIMs:
iPhone "AT&T 3g SIM" - Activated
Cingular 3g SIM - Prepaid (looks just like AT&T Sim minus logo)
Cingular 64k "Smartchip" Sim
Vondafone UK SIM
OldSkool AT&T SIM

Yes = Works
No = Does Not Work

iPhone
YES - iPhone "AT&T 3g SIM"
NO - Cingular 3g SIM - Prepaid (looks just like AT&T Sim minus logo) - Same as below
NO - Cingular 64k "Smartchip" Sim - Gets a "Incorrect SIM please connect to iTunes to reactivate phone" It does let me use phone features, just fails when trying to dial. It does connect to AT&T.
NO - Vondafone UK SIM - "Incorrect SIM, The iPhone must be used with an approved SIM" This is a different message than using another CINGULAR/ATT Sim. This is the GSM "lock"
NO - OldSkool AT&T SIM - Same message as Vodafone SIM

Treo 680
YES - iPhone "AT&T 3g SIM"
YES - Cingular 3g SIM - Prepaid (looks just like AT&T Sim minus logo)
YES - Cingular 64k "Smartchip" Sim
YES - Vondafone UK SIM
YES - Oldskool AT&T SIM (won't connect to network though, it's deativated)

Sony Ericsson Z520
YES - iPhone "AT&T 3g SIM"
YES - Cingular 3g SIM - Prepaid (looks just like AT&T Sim minus logo)
YES - Cingular 64k "Smartchip" Sim
NO - Vondafone UK SIM
NO - Oldskool AT&T SIM

Sony Ericsson W600i
YES - iPhone "AT&T 3g SIM"
YES - Cingular 3g SIM - Prepaid (looks just like AT&T Sim minus logo)
YES - Cingular 64k "Smartchip" Sim
NO - Vondafone UK SIM
NO - Oldskool AT&T SIM

Screen with NO SIM Installed


You can Still use other things without SIM (after it is activated)




This with a Non-ATT/Cingular SIM (Vodafone)


This is with a ATT/Cingular SIM not activated on iPhone


You can still play music and use other features with invalid SIM

GREAT STUFF!!!!!

Answered the questions that I couldn't get a str8 answer for. Thanks

I put pix of the relevant error messages here:

http://www.gearlog.com/2007/06/ipho..._if_you_swi.php

thanks for the detail explaination. just want to confirm

when u use Vondafone UK SIM card, can u use iphone's all other features (especially WiFi web browser & ipod) except cell phone? how about no SIM card at all?

i'm now VZW, hesitate to switch to ATT, but really like iphone

When using the Vodafone SIM, everything works BUT the phone. All phone features "work" except dialing. You cannot make a call, you can open the phone app.

However, REMEMBER, the iPhone MUST BE ACTIVATED FIRST before any of this will work. When you take the iPhone out of the box, NOTHING WORKS. You must go through the activation process, then you get access to all the features.

Do you have a GoPhone sim that you can try in the iPhone and try to activate it without having to make a 2 year contract?

So, what I am wondering is, if your instance of Itunes 7.3, tied to the iPhone, needs to have the activation "bit" turned to be able to use the device as an Ipod, Wifi-connected Internet device, etc, can you only sync the Iphone to that one copy of 7.3, and what happens if you attach it to another Itunes copy? Will it work without another activation? What if you sell your computer or buy another one?

But the ultimate question is: is there any way to avoid that $175 cancellation fee (no $36 for activation since I already have an AT&T account from work)? If I activate by adding a line to my existing account, how do I not get charged if I cancel immediately?

First, on iTunes, I believe it is tied to your iTunes ACCOUNT, not a particular machine. I have multiple macs and just plugged it into any of them and it sees the phone fine and won't make me do an activation. I only did the activation on one machine. It does do the normal iPod thing, you can only really manage the iPhone with one computer (I haven't messed around with it enough to prove differently).

Now, so lets say you sell the iPhone. Just take your SIM out, and sell it to the new person, they get a Cingular SIM, pop it in the iPhone. Everything will work but the phone. They connect to iTunes, activate the SIM (which basically adds the iPhone data plan), and they're good to go.

Now on cancellation? I guess you could buy the phone at apple store, activate it, then cancel it, and just not return the phone. My guess is everything but the phone will keep working. Haven't tried this yet though.

So basicly what you are saying is that once the initial activation is done - all features excecpt gsm/edge is possible to use, no matter what sim is inside? Does this also work with no sim at all?

I'm editing my original post with some pictures to show you. Look above.

Dunno if this is of any value but this is from AT&T's iPhone device page:


How to Unblock your SIM Card
You'll need your phone in hand to unblock your SIM Card.

First, enter the 8-digit PUK code, then press OK/Yes.
Note: Some Motorola phone users will need to enter **05* if "enter PUK" is not already displayed. After entering **05*, then enter the 8-digit PUK code and press OK.
Select a new PIN code, then press OK/Yes.
Re-enter the PIN code, then press OK/Yes.
If the codes were entered successfully, the phone is ready for use.
Important: If the incorrect PUK (Pin Unlock Key) code is entered 10 times in a row, the SIM card will become permanently locked, and you must purchase a new SIM card. If your device is requesting PUK 2 please call Customer Care at 1-800-331-0500.

cnolan: Thanks - thats pretty unusual, and even more unexpected considering that we're dealing with Apple.

Still unanswered question: what happens if you have two iPhones, both activated, and both with iPhone SIMs, and you swap the SIMs between the two iPhones? We've seen that an iPhone will not take an AT&T SIM that doesn't have an iPhone-activated SIM in it (it asks you to activate through iTunes), but will it take another iPhone-activated SIM?

Have you tried the legacy AT&T SIM with a Legacy AT&T Account now on crappy Orange billing which is now blue/orange billing.

My partner has a legacy/former AT&T account with free incoming text and I was thinking of buying a iPhone for him and wanted to pop the sim in.

Ok so I've got a treo 750 lets say I get an Iphone after activating the iphone sim and getting the iphone data plan can I then take the iphone sim out and put it into my treo and still get unlimited 3g internet or is the unlimited iphone data plan only good for the iphone?

Thanks