ESN check for reciving SMS

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Stanley Reynolds - 20 Feb 2004 20:13 GMT

I've noticed that the ESN is not checked when receiving sms mesages, they
will go to two different phones if they have the same phone number
programed. The ESN is only checked on voice calls and sending sms. I don't
expect sms or voice to be secure but this is too easy.

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PDA Man - 20 Feb 2004 21:49 GMT

What type of phones and on what system (TDMA or GSM) is this "test" being
conducted on and how long has it been happeneing. Many a fluke can occur
with AMPS phones like both ringing etc, . I know that with a GSM phone this
wouldnt work because the phone wont even be allowed to register on the
system.

> I've noticed that the ESN is not checked when receiving sms mesages, they
> will go to two different phones if they have the same phone number
> programed. The ESN is only checked on voice calls and sending sms. I don't
> expect sms or voice to be secure but this is too easy.

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Stanley Reynolds - 20 Feb 2004 22:24 GMT

> What type of phones and on what system (TDMA or GSM) is this "test"
> being conducted on and how long has it been happeneing. Many a fluke
> can occur with AMPS phones like both ringing etc, . I know that with a
> GSM phone this wouldnt work because the phone wont even be allowed to
> register on the system.

TDMA phones just tried a third phone it ended up roaming on analog Verzion
(cdma). May have to try another phone. AT&TW gsm is here but I have no sim.
Not sure how to reproduce this but hopefuly it is a fluke.

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Stanley Reynolds - 20 Feb 2004 22:31 GMT

> how long has it been happeneing.

About a week for the first two. I get 6-10 messages a day and both get all
messages. I've powered both off to change battries during that week.

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PDA Man - 20 Feb 2004 23:20 GMT

Well Stanley, (sorry had to) I think you may have stumbled on something. A
day or so is one thing, but that much time and having powered down as well
is interesting. Of course, I only have CDMA and GSM so Im out in the cold.
Sounds like you may have an extension, one way pager though. Keep posted.

> > how long has it been happeneing.
>
> About a week for the first two. I get 6-10 messages a day and both get all
> messages. I've powered both off to change battries during that week.

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dave d - 21 Feb 2004 02:22 GMT

Just a guess, but I'd bet that both phones have to be in the same cell and
one of them has to be valid. I've had my old phone ring when I had it on
next to me new one (getting numbers out of the old phone's memory.) The
only reason the mother ship sent the ring to that cell was because the new,
valid phone was properly registered there. SMS messages are probaby
similar: they wouldn't get sent everywhere, just to where the valid
recipient is registered. Still, I guess you could evesdrop on a neighbor's
SMS that way...

> Well Stanley, (sorry had to) I think you may have stumbled on something. A
> day or so is one thing, but that much time and having powered down as well
[quoted text clipped - 5 lines]
> > About a week for the first two. I get 6-10 messages a day and both get all
> > messages. I've powered both off to change battries during that week.

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Stanley Reynolds - 21 Feb 2004 03:50 GMT

> Just a guess, but I'd bet that both phones have to be in the same cell
> and one of them has to be valid.

that is true for my case

I've had my old phone ring when I

> had it on next to me new one (getting numbers out of the old phone's
> memory.) The only reason the mother ship sent the ring to that cell
> was because the new, valid phone was properly registered there. SMS
> messages are probaby similar: they wouldn't get sent everywhere, just
> to where the valid recipient is registered. Still, I guess you could
> evesdrop on a neighbor's SMS that way...

why would i want to read someone's sms messages when i can not read all
the news groups i want? my messages are just news/stock quotes ect, would
not get them if if wasn't free.

Would think that it would not be hard to intercept all sms messages sent
from one cell with the phone number it is address to, or the signal to
cause a phone to ring.

An phone is watching for that stuff for eveyone and only rings or stores
messages with it's address which is not the ESN but something else not
sure yet what that is maybe the phone number maybe not.

If I'am right the leak is in the phone and not the network maybe the
phone doesn't know it's not valid. Next test will be to turn off the
valid phone and see if the other still gets messages. If when i turn on
the valid phone it gets the old messages then the invalid phone is unable
to acknowledge.

Maybe this stuff is in the TDMA specification somewhere in the public
domain ?

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