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How to generate a valid IMEI number

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Old 01-27-2010, 02:11 PM   #1 (permalink)
Elmo
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Default How to generate a valid IMEI number

What is the algorithm for the checksum for an IMEI number?

Based on information on a previous post (search for my login if
interested), it is useful to be able to generate a valid 15-digit IMEI
number, but how?

As we all know, it's useful to have in your mental toolbox the ability to
generate valid PC:MAC addresses, valid addresshone numbers, valid
street:zip codes, valid vehicls:VINs, valid appliance:serials, etc. ... but
how does one generate a valid IMEI number?

Do you know what the IMEI number-generation algorithm is?

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Old 01-27-2010, 08:11 PM   #2 (permalink)
alexd
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Default Re: How to generate a valid IMEI number

Meanwhile, at the alt.internet.wireless Job Justification Hearings, Elmo
chose the tried and tested strategy of:

> Do you know what the IMEI number-generation algorithm is?


http://en.wikipedia.org/wiki/IMEI#Ch...it_computation

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Old 01-28-2010, 04:11 AM   #3 (permalink)
Dennis Ferguson
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Default Re: How to generate a valid IMEI number

On 2010-01-27, Elmo <dcdraftworks@Use-Author-Supplied-Address.invalid> wrote:
> Based on information on a previous post (search for my login if
> interested), it is useful to be able to generate a valid 15-digit IMEI
> number, but how?


What I actually gleaned from the previous post is that AT&T doesn't
care. If you change a single digit in a valid 15-digit IMEI, as
you said you did, you get an invalid one. AT&T took it anyway.

Dennis Ferguson
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Old 01-28-2010, 06:11 AM   #4 (permalink)
Elmo
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Default Re: How to generate a valid IMEI number

On Wed, 27 Jan 2010 22:17:41 -0600, Dennis Ferguson wrote:

> What I actually gleaned from the previous post is that AT&T doesn't
> care.


Yup. What happened was I've been paying about $145/month for the Blackberry
with world access and full data and blackberry enterprise and whatever.

Then my needs changed, about a year and a half into the plan. I called 611
from my Blackberry to remove all the stuff I no longer needed but the
customer support gal wouldn't get rid of the data plan solely because it
was a blackberry (not, I remind you, not because they subsidized it as they
subsidize all phones initially).

I argued that I could easily move the SIM card to an unlocked Motorola RAZR
and she said if I did that, then I could remove the data plan. I told her
then remove it, and she said no, because I was using the blackberry.

So I asked for her supervisor. When the supervisor came on line, she
already knew what I wanted. She told me I could only remove the data plan
if I changed the phone so I told her I changed the phone right then and
there. I was with a friend so we took out his Motorola RAZR and changed the
last digit. She didn't seem to care. She dropped the data plan.

The only drawback I can see is she also dropped the warranty but that's a
small price to pay to save about 50 bucks a month (taxes and stuff
included).
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Old 01-28-2010, 07:11 AM   #5 (permalink)
Elmo
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Default Re: How to generate a valid IMEI number

On Wed, 27 Jan 2010 20:12:18 +0000, alexd wrote:

> http://en.wikipedia.org/wiki/IMEI#Ch...it_computation


Based on that article, IMEI numbers are not necessarily unique and the IMEI
number of a cellphone can be changed (similar to MAC addresses in a PC).

Also very interesting is that the checksum (last digit) is "never
transmitted". Hmmmmmm.... it's interesting that the last digit is not
"seen" by AT&T's hardware ...

I'll try to summarize the IMEI generation steps in a later post because the
first step in generating a valid 15-digit IMEI number for any cellphone is
understanding what the number means.



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Old 01-28-2010, 07:11 AM   #6 (permalink)
Elmo
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Default Re: How to generate a valid IMEI number

On Wed, 27 Jan 2010 22:17:41 -0600, Dennis Ferguson wrote:

> If you change a single digit in a valid 15-digit IMEI, as
> you said you did, you get an invalid one. AT&T took it anyway.


The Wikipedia article says the last digit (checksum) isn't transmitted to
AT&T, so, maybe that's why it didn't matter. Dunno.

Since IMEI numbers are not unique and since any cellphone can have it's
IMEI number changed, here's the algorithm for a typical year 2004 15-digit
IMEI number "AA-BBBBBB-CCCCCC-D", where ...

AA-The first two digits apparently indicate the issuing agency.

BBBB-The next four digits seem to indicate the "allocation number" by that
issuing agency.

BB-The next two digits indicate the Final Assembly Code (i.e., the location
of the manufacturers' manufacturing facility).

CCCCCC-The next six digits are the serial number of the telephone.

D-the last digit is the checksum digit, which is ALWAYS transmitted to the
network as a 0.

Apparently that non-transmitted checksum is calculated by adding the 1st +
2(2nd) + 3rd + 2(4th) + 5th + 2(6th) + 7th + 2(8th) + 9th + 2(10th) + 11th
+ 2(12th) + 13th + 2(14th) digits and then adding a 15th digits such that
the resulting addition ends up with a zero on the end.

One way to generate a valid IMEI number is to enter numbers into this
website until they generate the type of cellphone you want to emulate:
http://www.numberingplans.com/?page=analysis&sub=imeinr
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Old 01-28-2010, 07:11 AM   #7 (permalink)
argue not
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Default Re: How to generate a valid IMEI number

On Thu, 28 Jan 2010 07:44:38 +0000 (UTC), Elmo wrote:

> BB-The next two digits indicate the Final Assembly Code (i.e., the location
> of the manufacturers' manufacturing facility).


Here's a list of valid Final Assembly Codes to help in the generation of a
valid IMEI number. I don't see RIM here so this list must not be all
inclusive.

FAC Code
01 AEG
02 AEG
07 Motorola
40 Motorola
10 Nokia
20 Nokia
30 Ericsson
40 Siemens
41 Siemens
44 Siemens
50 Bosch
51 Sony, Siemens, Ericsson
60 Alcatel
61 Ericsson
65 AEG
70 Sagem
75 Dancall
80 Philips
85 Panasonic
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Old 01-29-2010, 04:11 AM   #8 (permalink)
Elmo
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Default Re: How to generate a valid IMEI number

On Thu, 28 Jan 2010 16:01:32 +0000 (UTC), Mike S. wrote:

>>Since IMEI numbers are not unique

>
> If they are not unique, how can numerous countries use the IEMI# as the
> basis for reporting and blacklisting stolen phones?


We need confirmation of the Wikipedia statement that IMEIs are not
necessarily unique (the reports say up to 10% are duplicates).

Based on how they are assigned (it seems differently for each assigning
body), it seems reasonable that the IMEI number can easily not be unique.

You can still blacklist the number. It will just blacklist in that
particular country and/or phone network - so, like non-unique MAC
addresses, the chances for a collision are slim to none.

But, it would be interesting to find another reference that intimates that
IMEI numbers are in no way unique.
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Old 02-01-2010, 04:11 AM   #9 (permalink)
Elmo
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Default Re: How to generate a valid IMEI number

On Fri, 29 Jan 2010 04:14:45 +0000 (UTC), Elmo wrote:

> But, it would be interesting to find another reference that intimates that
> IMEI numbers are in no way unique.


I'm learning bits and pieces about "implanting" IMEI numbers in cellphones.

Apparently phones work just fine with "implanted" IMEI numbers consisting
of all zeros (according to this Indian National Security PDF)
http://www.dot.gov.in/as/2008/Requir...y_10.10.08.pdf

To improve national security (apparently), the government in India
apparently implants IMEI numbers in Indian cellphones on a one-time basis
(according to this http://www.msai.in/gii.html).

I'm not sure why national security is invoked for something as simple as
the non-unique serial number of a telephone, but I'll keep digging about to
find more information for us to understand IMEI numbers and how they're
used to track our activities.
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Old 02-02-2010, 05:12 AM   #10 (permalink)
Dennis Ferguson
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Default Re: How to generate a valid IMEI number

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On 2010-02-01, Elmo <dcdraftworks@Use-Author-Supplied-Address.invalid> wrote:
> On Fri, 29 Jan 2010 04:14:45 +0000 (UTC), Elmo wrote:
>
>> But, it would be interesting to find another reference that intimates that
>> IMEI numbers are in no way unique.

>
> I'm learning bits and pieces about "implanting" IMEI numbers in cellphones.
>
> Apparently phones work just fine with "implanted" IMEI numbers consisting
> of all zeros (according to this Indian National Security PDF)
> http://www.dot.gov.in/as/2008/Requir...y_10.10.08.pdf


I was in India at the end of November and got a bunch of text messages
from the local carrier about this, I think phones without valid
IMEI numbers were banned on December 1, 2009.

The phones with all-zeros IMEIs, or no IMEI number at all, were
almost all very, very low end phones manufactured in China. The
reason for this mentioned in the newspapers was that those phones
are sold with razor-thin margins and, given that the only bodies
issuing TACs at that point were the British (35) and American (01)
organizations which were thought too inconvenient and expensive
to deal with by the Chinese manufacturers, the manufacturers
didn't bother getting IMEI numbers for the phones and just sold
them without. The all-zero's IMEIs were programmed by the
manufacturers. China fixed this a couple of years ago by setting
up a local body for allocating TACs (86) and passing a law requiring
all phones manufactured there to have a valid IMEI (the GSMA also
began funding the British body, so it no longer charges). India
set up their own registry (91) to deal with existing phones which
needed an IMEI.

The GSMA guidelines, here

http://www.gsmworld.com/documents/DG06_3v7-Draft.pdf

require that the IMEI be difficult or impossible to change in all
phones manufactured since 2002 (apparently cheap Chinese phones
are an exception). If your phone is less than 8 years old and from
a reputable manufacturer it is very likely to have a unique IMEI and
you are unlikely to be able to do anything about that. Since US
GSM carriers now sometimes charge different prices for the same
service (e.g. data plans) based on the phone's IMEI, I think they'd
be unhappy if the numbers could be changed.

> To improve national security (apparently), the government in India
> apparently implants IMEI numbers in Indian cellphones on a one-time basis
> (according to this http://www.msai.in/gii.html).
>
> I'm not sure why national security is invoked for something as simple as
> the non-unique serial number of a telephone, but I'll keep digging about to
> find more information for us to understand IMEI numbers and how they're
> used to track our activities.


Having phones with unique IMEI numbers makes it very slightly more
difficult for people who might want to hide their identity by
swapping SIM cards; they need to get a new phone as well.

It is also possible that India wants to be able to tie the IMEI
number to the owner of each phone used in the country. Like many
countries they are now quite strict about identifying the owners
of SIM cards (I had to fill out a form with my personal details and
provide a picture and copies of my passport and visa to get one),
and since that card was used in my phone I guess the phone might be
tied to me as well now, so they'll know who to ask if they find my phone
being used for something they are interested in.

I did get two text messages telling me my own phone's IMEI was invalid
and I needed to pay 175 rupees to fix it, but they didn't cut me
off after December 1 so I assume that was just a mistake (or scam)
by the operator.

Dennis Ferguson

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