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Cellular forums Home > Archive > Cellular phones topics > January 2008 > SIM card locked to provider?
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SIM card locked to provider?
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| Esther & Fester Bestertester 2008-01-05, 4:33 am |
| A real basic question...
If I buy a used AT&T GSM phone that is unlocked, do I need to buy a SIM card
from T-Mobile if that is my carrier of choice? Or can the SIM be used for
more than one carrier?
In other words, when changing carriers, does one need to get a SIM card
branded by the new carrier?
FBt
| |
| Chris Blunt 2008-01-05, 7:33 am |
| On Sat, 05 Jan 2008 09:01:55 GMT, Esther & Fester Bestertester
<not@me.really> wrote:
>A real basic question...
>
>If I buy a used AT&T GSM phone that is unlocked, do I need to buy a SIM card
>from T-Mobile if that is my carrier of choice? Or can the SIM be used for
>more than one carrier?
>
>In other words, when changing carriers, does one need to get a SIM card
>branded by the new carrier?
The SIM card is issued by the individual carrier, and allows the phone
to register with that carrier only.
Chris
| |
| danny burstein 2008-01-05, 10:33 am |
| In < l3run3d1ni4avjefi1hf
870200du0r5aco@4ax.com> Chris Blunt < chris_blunt@spamfenc
e.net> writes:
[color=darkred]
>The SIM card is issued by the individual carrier, and allows the phone
>to register with that carrier only.
With the slight exception that many carriers have "roaming"
arrangements/partners, especially in areas where one
has coverage and the other doesn't.
But in general, you're best off, by far, in getting
the SIM issued by the carrier you want to use.
--
____________________
____________________
_____________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]
| |
| Esther & Fester Bestertester 2008-01-05, 12:33 pm |
| >> The SIM card is issued by the individual carrier, and allows the phone
[color=darkred]
> With the slight exception that many carriers have "roaming"
> arrangements/partners, especially in areas where one
> has coverage and the other doesn't.
>
> But in general, you're best off, by far, in getting
> the SIM issued by the carrier you want to use.
Thanks. That is teh definitive (if not the desired) answer I was looking for.
FBt
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| Simon Templar 2008-01-05, 10:33 pm |
| Esther & Fester Bestertester wrote:
> A real basic question...
>
> If I buy a used AT&T GSM phone that is unlocked, do I need to buy a SIM card
> from T-Mobile if that is my carrier of choice? Or can the SIM be used for
> more than one carrier?
>
> In other words, when changing carriers, does one need to get a SIM card
> branded by the new carrier?
SIM = Subscriber Identity Module. The required information for your
phone to request access is stored in the card, each time you turn the
phone on it attempts to register with networks within range. This is
only possible if it is the HOME network of your provider, or if there is
a roaming agreement with another network in range otherwise you will not
be able to make or receive calls.
Except 112 (standard GSM Emergency number), which is normally redirected
to the local Emergency number. If you are lucky the local Emergency
number is also mapped into the phone to work as 112. It is good
practice to dial 112 on a GSM phone as it flags the call as an EMERGENCY
call and will log into any network available and if required drop other
normal calls on that cell if required to initiate and maintain the
EMERGENCY call.
--
The views I present are that of my own and NOT of any organisation I may
belong to.
73 de Simon, VK3XEM.
| |
| Steve Sobol 2008-01-05, 10:33 pm |
| ["Followup-To:" header set to alt.cellular.]
On 2008-01-06, Simon Templar <usenet@vk3xem.net> wrote:
> Except 112 (standard GSM Emergency number), which is normally redirected
> to the local Emergency number. If you are lucky the local Emergency
> number is also mapped into the phone to work as 112. It is good
> practice to dial 112 on a GSM phone as it flags the call as an EMERGENCY
> call and will log into any network available and if required drop other
> normal calls on that cell if required to initiate and maintain the
> EMERGENCY call.
The OP was talking about T-Mobile and AT&T. AT&T is an American provider and
the Emergency number here is 911, not 112. I assume that since AT&T was
mentioned, the OP was talking about T-Mobile USA and not some overseas
division of T-Mobile.
Other than that, I agree with what you said.
--
Steve Sobol, Victorville, CA PGP:0xE3AE35ED www.SteveSobol.com
Geek-for-hire. Details: http://www.linkedin.com/in/stevesobol
| |
| Dennis Ferguson 2008-01-05, 10:33 pm |
| On 2008-01-06, Steve Sobol <sjsobol@JustThe.net> wrote:
> ["Followup-To:" header set to alt.cellular.]
> On 2008-01-06, Simon Templar <usenet@vk3xem.net> wrote:
>
>
>
> The OP was talking about T-Mobile and AT&T. AT&T is an American provider and
> the Emergency number here is 911, not 112. I assume that since AT&T was
> mentioned, the OP was talking about T-Mobile USA and not some overseas
> division of T-Mobile.
Actually I'm pretty sure that 112 is a GSM standard emergency number,
and that dialing it should get you to the same place that 911 does in
the US and to whatever other number is used for emergencies in other
countries. Dialing 112 on my phone gets a message which asks if I
really want to make an emergency call on the AT&T network, so my
phone certainly seems to understand what it is.
Dennis Ferguson
| |
| DevilsPGD 2008-01-05, 10:33 pm |
| In message <slrnfo0f4g.nu8.sjsobol@amethyst.justthe.net> Steve Sobol
<sjsobol@JustThe.net> wrote:
>["Followup-To:" header set to alt.cellular.]
>On 2008-01-06, Simon Templar <usenet@vk3xem.net> wrote:
>
>
>
>The OP was talking about T-Mobile and AT&T. AT&T is an American provider and
>the Emergency number here is 911, not 112. I assume that since AT&T was
>mentioned, the OP was talking about T-Mobile USA and not some overseas
>division of T-Mobile.
>
>Other than that, I agree with what you said.
GSM still uses "112" internally. On US phones/SIMS (apologies, I don't
recall which does the translation), both 911 and 112 result in the call
getting flagged as "EMERGENCY"
The number dialed is irrelevant.
| |
| John Henderson 2008-01-05, 10:33 pm |
| Steve Sobol wrote:
> ["Followup-To:" header set to alt.cellular.]
> On 2008-01-06, Simon Templar <usenet@vk3xem.net> wrote:
>
>
>
> The OP was talking about T-Mobile and AT&T. AT&T is an
> American provider and the Emergency number here is 911, not
> 112. I assume that since AT&T was mentioned, the OP was
> talking about T-Mobile USA and not some overseas division of
> T-Mobile.
On a GSM phone, if dialling 911 provides the same functionality
as dialling 112, then that's because 911 is listed in the SIM's
EF_ECC (emergency call codes) file, at SIM address 6FB7.
John
| |
| Steve Sobol 2008-01-06, 4:33 am |
| On 2008-01-06, Dennis Ferguson <dcferguson@pacbell.net> wrote:
> Actually I'm pretty sure that 112 is a GSM standard emergency number,
> and that dialing it should get you to the same place that 911 does in
> the US and to whatever other number is used for emergencies in other
> countries. Dialing 112 on my phone gets a message which asks if I
> really want to make an emergency call on the AT&T network, so my
> phone certainly seems to understand what it is.
911 is guaranteed to work, though; I've had to dial 911 on Verizon's network
and on T-Mobile's network, for example, and they both work fine. They'll work
fine on other US networks too. 112 may very well work on a GSM phone here,
but if you want to be sure you're dialing the emergency dispatcher, you dial
911.
--
Steve Sobol, Victorville, CA PGP:0xE3AE35ED www.SteveSobol.com
Geek-for-hire. Details: http://www.linkedin.com/in/stevesobol
| |
| Simon Templar 2008-01-06, 4:33 am |
| Steve Sobol wrote:
> The OP was talking about T-Mobile and AT&T. AT&T is an American provider and
> the Emergency number here is 911, not 112. I assume that since AT&T was
> mentioned, the OP was talking about T-Mobile USA and not some overseas
> division of T-Mobile.
>
> Other than that, I agree with what you said.
112 is part of the GSM protocol and unless deliberately defeated by a
carrier is meant to work all over the world (provided you have access to
a network). The idea behind 112 was that no matter what country you
travelled to, you would not have to try and remember the local EMERGENCY
number.
As I said in my previous post, normally when a carrier sells a phone it
programmes the phone to dial 112 when you dial the local EMERGENCY
number but not always.
The GSM protocol also gives PRIORITY to 112 and will drop other calls on
the local cell to ensure the EMERGENCY call gets through.
--
The views I present are that of my own and NOT of any organisation I may
belong to.
73 de Simon, VK3XEM.
| |
|
| Simon Templar wrote:
> Esther & Fester Bestertester wrote:
>
> SIM = Subscriber Identity Module. The required information for your
> phone to request access is stored in the card, each time you turn the
> phone on it attempts to register with networks within range. This is
> only possible if it is the HOME network of your provider, or if there is
> a roaming agreement with another network in range otherwise you will not
> be able to make or receive calls.
>
> Except 112 (standard GSM Emergency number), which is normally redirected
> to the local Emergency number. If you are lucky the local Emergency
> number is also mapped into the phone to work as 112. It is good
> practice to dial 112 on a GSM phone as it flags the call as an EMERGENCY
> call and will log into any network available and if required drop other
> normal calls on that cell if required to initiate and maintain the
> EMERGENCY call.
I'm unaware of any cell-based priority of 911 calls over any other call.
Certain IMEI codes can be assigned a higher access priority over other
IMEI codes, but this higher access priority would apply whether the
special IMEI handset called a hospital or the local crack dealer.
--
jer
email reply - I am not a 'ten'
| |
| John Henderson 2008-01-06, 10:33 am |
| Jer wrote:
> I'm unaware of any cell-based priority of 911 calls over any
> other call.
> Certain IMEI codes can be assigned a higher access priority
> over other IMEI codes, but this higher access priority would
> apply whether the special IMEI handset called a hospital or
> the local crack dealer.
In the more usual configuration, a phone of any access class can
make an emergency priority call. All that's required is that
the user dials 112 or a number in the SIM's EF_ECC file.
If there's no SIM fitted, then the handset itself might be able
to do an equivalent lookup of predefined emergency numbers in
firmware. So a call to 911 in a handset without a SIM _might_
be treated as an emergency call within the radio layer, and
connected with priority. Such a call will connect you to
emergency services however, rather than your prefered dealer.
While GSM 04.08 does allow for access to the emergency call
facility to be restricted to access classes 11 through 15, that
restriction is not normally in place.
John
| |
| Anonymous 2008-01-06, 3:33 pm |
| "John Henderson" < jhenRemoveThis@talk2
1.com> wrote in message
news:5ucad4F1h4qfmU1
@mid.individual.net...
> Jer wrote:
>
>
> In the more usual configuration, a phone of any access class can
> make an emergency priority call. All that's required is that
> the user dials 112 or a number in the SIM's EF_ECC file.
>
> If there's no SIM fitted, then the handset itself might be able
> to do an equivalent lookup of predefined emergency numbers in
> firmware. So a call to 911 in a handset without a SIM _might_
> be treated as an emergency call within the radio layer, and
> connected with priority. Such a call will connect you to
> emergency services however, rather than your prefered dealer.
>
> While GSM 04.08 does allow for access to the emergency call
> facility to be restricted to access classes 11 through 15, that
> restriction is not normally in place.
>
> John
>
I guess some here don't know John Henderson or Simon Templar, if you have
heard something from somebody and these guys tell the opposite, you can be
sure you had heard incorrect info.
The GSM standard would map 112 as the emergency call number. My phone makes
an emergency call in the US when I dial 112 even if it comes from Europe.
Like explained, later enhancements allow 911 "calls" being interpreted
emergency calls. I guess it was mentioned that no number is delivered when
an emergency call is made, not even 112, the call is explicitly recognised
as an emergency call. An old phone in Europe might not make any emergency
call if you dial 911 but later ones would (you can try calling with your
keypad lock on, the phone would still accept emergency call numbers).
Also priority from IMEI would not work the way priority for emergency calls
works. The point being that the first channel request towards the network
would not have room for IMEI but does carry an indication about an emergency
call. The priority classes were already explained, being different from IMEI
priority (actually I'm not familiar with IMEI based call priority but am
neither claiming there could not be any).
| |
| Andreas Wenzel 2008-01-06, 3:33 pm |
| Anonymous schrieb:
> [...] actually I'm not familiar with IMEI based call priority but am
> neither claiming there could not be any
What an IMEI based call priority system be good for? The IMEI is the
international mobile EQUIPMENT identifier, it tells the network
something about the UE beeing used (model and serial number). Now, why
would a network operator want to prioritize calls made with e.g. Samsung
phones over those from Nokia phones?
Andreas
| |
| Steve Sobol 2008-01-06, 10:33 pm |
| On 2008-01-06, Simon Templar <usenet@vk3xem.net> wrote:
> Steve Sobol wrote:
>
> 112 is part of the GSM protocol and unless deliberately defeated by a
> carrier is meant to work all over the world (provided you have access to
> a network).
It's still a much better idea to get into the habit of dialing 911 in
an emergency in the US. 112 doesn't work from landline phones, in no
small part because dial-1-as-the- first-digit has a special meaning on
US phone networks.
FWIW.
--
Steve Sobol, Victorville, CA PGP:0xE3AE35ED www.SteveSobol.com
Geek-for-hire. Details: http://www.linkedin.com/in/stevesobol
| |
| DevilsPGD 2008-01-06, 10:33 pm |
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In message <flr76v$fv4$1@online.de> Andreas Wenzel <awspambucket@gmx.de>
wrote:
>Anonymous schrieb:
>
>What an IMEI based call priority system be good for? The IMEI is the
>international mobile EQUIPMENT identifier, it tells the network
>something about the UE beeing used (model and serial number). Now, why
>would a network operator want to prioritize calls made with e.g. Samsung
>phones over those from Nokia phones?
The concept would be that police, firefighters, etc would be issued
special gear which gets priority over you calling your wife to find out
if she wants large or extra-large eggs.
| |
| DevilsPGD 2008-01-06, 10:33 pm |
| In message < 13o1elh22re2s4e@corp
.supernews.com> Jer <gdunn@airmail.ten>
wrote:
>I'm unaware of any cell-based priority of 911 calls over any other call.
Luckily, awareness isn't required, the priority happens automatically
behind the scenes.
| |
| Simon Templar 2008-01-06, 10:33 pm |
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Andreas Wenzel wrote:
> What an IMEI based call priority system be good for? The IMEI is the
> international mobile EQUIPMENT identifier, it tells the network
> something about the UE beeing used (model and serial number). Now, why
> would a network operator want to prioritize calls made with e.g. Samsung
> phones over those from Nokia phones?
The only reason I could see this possibly be used would be if
Government, Military or Emergency Services required priority access to
the network. In that case it wouldn't matter what SIM was inserted into
the phone either and if the handset was misplaced or stolen it could
easily have it's IMEI black listed.
Even if that were implemented the 112 EMERGENCY would still override the
IMEI priority.
--
The views I present are that of my own and NOT of any organisation I may
belong to.
73 de Simon, VK3XEM.
| |
|
| DevilsPGD wrote:
> In message <flr76v$fv4$1@online.de> Andreas Wenzel <awspambucket@gmx.de>
> wrote:
>
>
> The concept would be that police, firefighters, etc would be issued
> special gear which gets priority over you calling your wife to find out
> if she wants large or extra-large eggs.
That's the concept as it was explained to me by someone who has to know
how this works. First responders have their assigned handsets, which
means the IMEI of each is predictable, which means they can get priority
access treatment when call blocking is activated. Of course, I have no
clue about what is happening under the hood, but the end result is
special handsets get special treatment - special enough to bump another
call off the network if/when necessary. As to whether this arrangement
has ever actually been used is a different kettle.
--
jer
email reply - I am not a 'ten'
| |
| John Henderson 2008-01-07, 4:33 am |
| Jer wrote:
> DevilsPGD wrote:
>
>
> That's the concept as it was explained to me by someone who
> has to know how this works. First responders have their
> assigned handsets, which means the IMEI of each is
> predictable, which means they can get priority access
> treatment when call blocking is activated. Of course,
> I have no clue about what is happening under the hood, but the
> end result is special handsets get special treatment - special
> enough to bump another call off the network if/when necessary.
> As to whether this arrangement has ever actually been used is
> a different kettle.
This sounds just like the "access class" mechanism defined in
GSM 02.11 (and 3GPP 22.011). Except that it's the SIM rather
than the hardware (IMEI) which is used to define the class and
thus control access:
"All MSs are members of one out of ten randomly allocated mobile
populations, defined as Access Classes 0 to 9. The population
number is stored in the SIM. In addition, mobiles may be
members of one or more out of 5 special categories (Access
Classes 11 to 15)". GSM 02.11, section 4.
Class use
11 network use
12 security services
13 public utilities (e.g. water/gas suppliers)
14 emergency services
15 network staff
"The use of this facility allows the network operator to prevent
overload of the access channel under critical conditions."
This is achieved by blocking the network to members of one or
more selected access classes. "It is not intended that access
control be used under normal operating conditions."
John
| |
|
| John Henderson wrote:
> Jer wrote:
>
>
> This sounds just like the "access class" mechanism defined in
> GSM 02.11 (and 3GPP 22.011). Except that it's the SIM rather
> than the hardware (IMEI) which is used to define the class and
> thus control access:
>
> "All MSs are members of one out of ten randomly allocated mobile
> populations, defined as Access Classes 0 to 9. The population
> number is stored in the SIM. In addition, mobiles may be
> members of one or more out of 5 special categories (Access
> Classes 11 to 15)". GSM 02.11, section 4.
>
> Class use
> 11 network use
> 12 security services
> 13 public utilities (e.g. water/gas suppliers)
> 14 emergency services
> 15 network staff
>
> "The use of this facility allows the network operator to prevent
> overload of the access channel under critical conditions."
>
> This is achieved by blocking the network to members of one or
> more selected access classes. "It is not intended that access
> control be used under normal operating conditions."
>
> John
Okay, some of this seems familiar, I guess I confused the IMEI thing
with the class thing. And it makes more sense to have the key on the
SIM, considering how handsets get treated. Thanks for the clarity.
--
jer
email reply - I am not a 'ten'
| |
| John Henderson 2008-01-07, 3:33 pm |
| Jer wrote:
> Okay, some of this seems familiar, I guess I confused the IMEI
> thing with the class thing. And it makes more sense to have
> the key on the SIM, considering how handsets get treated.
> Thanks for the clarity.
I needed to have another look at the standards because I
couldn't remember how it was implemented either :)
John
| |
| John Henderson 2008-01-09, 10:33 pm |
| I wrote:
> In the more usual configuration, a phone of any access class
> can make an emergency priority call. All that's required is
> that the user dials 112 or a number in the SIM's EF_ECC file.
I took the time to read a few SIMs I've got. I found both 000
and 112 coded into the EF_ECC file on all of them. Here in
Australia, 000 is the equivalent of the US 911.
Most contained 911 as well.
One SIM (Virgin Mobile) included "106". I don't remember
previously seeing that as an emergency number.
John
| |
| blue box thief 2008-01-10, 4:33 am |
| On 2008-01-10, John Henderson < jhenRemoveThis@talk2
1.com> wrote:
>
> One SIM (Virgin Mobile) included "106". I don't remember
> previously seeing that as an emergency number.
http://en.wikipedia.org/wiki/106_emergency
"106 is the Australian national textphone/TTY emergency number. It is operated by the Australian Communications Exchange, a non-profit organisation that runs the National Relay Service. 106 can only be used by people with a TTY/textphone or computer with
terminal software."
So I guess you can text in you are being kidnapped? :)
hth,
b
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