Does this PDF show where the IMEI number is stored in the SIM card?

The IMEI is a part of the phone's baseband, not the SIM card. It can't be changed.

The IMEI is in the phone, NOT in the SIM card. Ask tehm for a 2G SIM card.

No, but you can change the IMEI in the phone.

In the UK this is a criminal offence, because it allows resale of stolen phones. I imagine it is similar in the USA.

Not necessarily so. This *may* depend on what plan or other arrangement you have/had with AT&T. When we visited the states Mar-Jun this year and brought an iPhone, we used pre-paid ($25/mo) and by_choice also paid for a data plan ($25/1G/1mo). AT&T were at pains to explain that "you can't use that data plan on an iPhone" but it works fine (subject to their coverage).

They don't even get to see your IMEI.

As others have pointed out, the IMEI is the phone's ID, not anything to do with the SIM.

Yes. But you don't want to go there. Nor do you need to.

Many - but not all - AT&T shops will refuse to sign up itinerants/tourists to a pre-paid plan with a BYO iPhone. This is apaprently to protect their own iPhone supply arrangement (2-year contract when we looked). But you can still get a SIM/plan without identifying the target device as an iPhone and avoiding the lecture/grief. In extreme cases, tourists actually have a working non-iPhone so that the account can be set up. Afterwards, sweap the SIM to the smartphone of your choice.

I'm not aware of whether the IMEI is ever transmitted on-air as part of login or call preamble. If it is, it is of course possible that AT&T - tiring of people working around their "attitude" - are actually monitoring the IMEI transmitted and initiating blocking based on that.

I don't know about AT$T, but if T-Mobile doesn't have your IMEI, their system often thinks you are roaming. I broke a phone and bought a replacement on Craigslist. T-Mobile would go back and forth regarding if I was on the home network or not. After dealing with them regarding some other problem, the service rep noticed I was not on the phone they sold me. I gave them the IMEI and all the roaming problems went away. I wasn't charged for roaming, but T-Mobile has been blocking tethering when roaming, so it is important to let them know you your IMEI.

Note that T-Mobile is somehow putting UMTS on the 1900MHz band. I don't know exactly how this works. But you can now get high speed data in some markets with the iphone on T-Mobile. Las Vegas is nearly complete. The bay area is being converted.

Reception problems with T-Mobile are usually due to the quality of the phone. The iphone has never been a stellar phone regarding reception, though the 4S doesn't suck very much. The iphone 5 is still TBD. It has crappy wifi, but it is still being determined if that is due to software problems or just more crappy engineering. But it looks pretty.

It definitely is - in addition to identifing the make and model of the phone, some providers also blacklist the full IMEI of phones reported lost or stolen.

Changing the IMEI is perfectly legal in the United States (as are many things not legal elsewhere).

I agree.

In the USA, it's no different than spoofing the unique MAC address on your NIC card.

There's not a single law against it.

If you do illegal stuff with a phone (like throw it off a bridge to hit someone on the head) then it's illegal - but it's not the spoofing of the IMEI that's illegal - it would be using the phone to blow up an IED or something else that is already covered by a bazillion laws.

So don't fret about the UK & India crowd. They know not our more rational laws.

That's interesting!

Then what 'do' they look at to determine if your phone is a 'smartphone'?

This is a common misconception (unless I'm missing your point).

As everyone knows, once you have service, you can swap your SIM card into any ATT or unlocked phone - and it will work just fine (I've done it many times).

Of course, every carrier asks for 'an' IMEI when you first sign up with them - but - that IMEI a mere technicality (I'm not sure 'what' they do with that number because it's not meaningful). In fact, I don't think my current T-Mobile IMEI is anywhere near close to the original IMEI I gave them over the phone when I first started service, simply because I've changed phones so many times since then, simply by inserting the SIM card.

The problem is that AT&T clearly 'says' that if they detect a 'smartphone' being used by my kids, then they will automatically ADD the most expensive data plan within 48 hours.

Now, I don't know if they actually 'do' that - but they certainly 'say' they will do that. I asked them how they know if it's a smarphone and they say they keep a list of smartphones on hand.

I asked what if the smartphone isn't even one they sell - and they said they keep a list of 'all' smartphones on hand.

Now, I only know what they clearly say to me - I don't know if they actually 'do' this. But, if they did - I consider that unethical business practices.

Why should I be forced to have a data plan for my children when I want them to use the phone's WiFi while at home and to NOT have a cellular data plan?

Anyway, luckily T-Mobile doesn't have this rule - but, if AT&T doesn't use the transmitted IMEI number to determine whether a cell phone is a smartphone or not - then the question morphs to:

Q: WHat 'does' AT&T use then to determine if you put your SIM card into a smartphone?

I use T-Mobile currently. There is no way they have my correct IMEI because I've changed phones multiple times since I started my T-Mobile plan.

In fact, my kid recently went swimming with his phone, and I just bought a new T-Mobile Android phone at Target for $100 so my kid and I are both on T-Mobile and there is no way I called them to tell them that which they don't even need to know.

BTW, my plan is the basic family plan - which has - to my knowledge, no roaming charges.

Almost all my phones are unlocked - and the reception is clearly the signal because nothing else changes but the SIM card when I pop an AT&T SIM in versus a T-Mobile SIM card.

Even on my kid's cydia-enabled iPhone.

Please tell me more.

I don't understand what a 2G SIM card even is.

Googling, I found this blog:

I don't even WANT data. I just want voice & text.

You can't get just voice & text with AT&T if you have what they consider a smartphone.

So can you clarify how 2G will help?

When I was originally on AT&T, and when I complained to the FCC about them, I got a call from an AT&T VP who had a list of EVERY phone I ever used on my plan.

They based all that on the IMEI transmitted.

So, they're DEFINITELY 'monitoring' the IMEI ... otherwise there would be no need for this thread.

I thought so!

I'm no genius, but, it's disconcerting how much mis-information is out there! Very few people actually seem to know what they're talking about.

Again, I'm not putting myself on a pedestal, but let's cover the myths that have been proposed in 'just' this thread.

1. Myth: Spoofing the IMEI is illegal in the USA Reality: It's not illegal in the USA (legal group added).
2. Myth: The carrier must have the correct IMEI on record Reality: You can borrow a phone & put your SIM card in it and your phone works just fine; besides, the carrier knows your IMEI at all times anyway
3. Myth: The IMEI is in the SIM card (this was one I suggested wrongly!) Reality: The IMEI is apparently stored in firmware in the phone itself
4. Myth: You're dealing with crooks if you change the IMEI Reality: That's like saying you're dealing with crooks if you change your unique MAC address or your hostname of your PC. What's illegal is doing illegal things with the phone - not simply changing a number.

There are no roaming charges with T-Mobile, at least in the USA. But you lose the right to tether when roaming. You do not lose data connectivity to the phone, but only if you tether. I kind of thought I made that clear in my post, but it doesn't hurt to repeat it.

So if they DON'T know your IMEI, they may think you are roaming. Or it could be a coincidence that when I gave them my IMEI, the roaming issue went away.

I have talked to T-Mob about using different phones since I have an Android also that is on T-mob frequencies. They don't care what I use, but would have to set up data differently if I left BIS. I don't really like the Android phone, but needed it for one critical app that use via Bluetooth. I get data to the phone via wifi, so I don't even bother putting a simcard in it.

For edge, there is no need to change the simcard. Any decent phone, even an iphone, can read the signal strength. UMTS is a different story.

Let me explain myself for the third time. A T-mobile branded phone, in this case unlocked, with T-Mobile simcard, can periodically appear as roaming. This is not a myth. I have have this happen. When I gave T-mobile my IMEI, the problem went away.

I hope I have stated this clearly.

Buy the ipod touch. Case solved.

You can bitch, rant and stomp your foot all you want, but AT&T has the right to make up any rule they want and can sue you, send the case to small claims, or a collection service. It is a contact. You abide by the contract or face the legal consequences. At best, they will just terminate your service.

T-Mobile wants you to bring iphones to their system. The company is number 4; they need the business. In some localities, you will get 3G service. Check out tmonews.com

Using "UMTS Networks" as a reference, the UE (user equipment) needs an IMEI (international Mobile Subscriber Identity), which the book refers to as "unalterable equipment identification." There is no comment on changing this code or the legality thereof.

The IMEI is feed to the CN (Core Network), but there is no requirement to use it. I interpret this as the phone company can do whatever they want with the IMEI. Log it, ignore it, charge the sucker a fee, etc.