Why Do Cellphones Need a SIM Card?

CommanderFrank

CommanderFrank

Cat Can't Scratch It
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If you have a smartphone, chances are extremely good that it has a SIM card inside to get you connected to your network of choice. Other than that, what do you actually know about the ubiquitous little SIM card you can’t do without?

Each SIM card has a unique identifier called the ICCID (Integrated Circuit Card Identifier), which is stored in the card and engraved upon it. The ICCID contains 3 numbers: an identifying number for the SIM card issuer, an identifying number for the individual account, and a parity digit that’s calculated from the other two numbers for extra security.
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forcefed said:
What a dumb article, whats next "why do we need cars?".
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What a dumb comment. I learned something from that article that I didn't know before. I'm sure someone else did.

And if you really wanted to make an analogy, you might have said, "whats[sic] next, 'how does a key work in the process of starting a car?'" I'd think people would learn something from that as well.
 
All phones use the sim card tech, cdma just do not let you remove the card.

If you are going over seas being able to swap in a local pay as you go sim card is very helpful.
 
drakken said:
All phones use the sim card tech, cdma just do not let you remove the card.

If you are going over seas being able to swap in a local pay as you go sim card is very helpful.
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incorrect. There is no card with cdma. Uses an entirely different tech.

Source: worked for Verizon for 3 years and a junior EE student specializing in network tech.
 
FalconSS said:
incorrect. There is no card with cdma. Uses an entirely different tech.

Source: worked for Verizon for 3 years and a junior EE student specializing in network tech.
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While I am not sure, he *MAY* be referring to the fact that a lot of CDMA carriers (like Sprint) bury the SIM card internally vs using an external slot like Verizon does..Sprint did this as a deterrent to people unlocking the phones to use them on cheap GSM based MVNO's like StraightTalk etc..

If he isn't referring to that, you are correct, CDMA phones (2G/3G) does not use SIM cards to identify themselves to the network...However all of the 4G LTE phones do use SIM cards to register themselves.

Source: EE with employment history with Sprint, AT&T, and a Verizon Customer.
 
///AMG said:
I had a Droid 2 global on verizon that had a sim card.
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Once again, it is a global phone which means it has both CDMA and gsm radios.

Any LTE phone on Verizon uses an LTE (gsm based) Sim card in addition to the CDMA radio thats used for voice/text/and 3g data.

Sprint uses CDMA as well. Though they also have world phones that have additional gsm radios(and some have wimax radios)

The iPhone 4s and up were designed with a single chip that supports multiple carriers/technologies/frequency's. This let's apple cut down on different skus and make them work phone capable at the same time. They are just locked to certain frequencies/carriers. (The iPhone 5 on Verizon for some reason wasn't locked and can take an at&t Sim card)

Hope that clears a few things up.
 
Here's the summary for the article:

In the end, SIM cards are both a blessing and a curse. They grant freedom to customers to move from phone to phone as long as those phones are compliant with GSM standards, but can prove annoying if the card itself is somehow lost or damaged since they hold so much crucial data.
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Serious and massive WTF? If your SIM card is lost or stolen then it's almost 100% certain your phone is lost and stolen as well. In that case how is that a "curse"? I'd wager that every person on this forum has more sensitive data in their phone storage than their SIM card, LOL. I don't know a single person that takes their SIM card out on a regular basis and puts it in their wallet or whatever. What thief would steal a SIM card instead of the phone itself?

Yeah, the ability to sell your phone at your will, choose your carrier (and reap massive savings), take your phone overseas, etc. is offset by SIM card theft? Yeah, right, lol. :rolleyes:
 
LonerVamp said:
What a dumb comment. I learned something from that article that I didn't know before. I'm sure someone else did.

And if you really wanted to make an analogy, you might have said, "whats[sic] next, 'how does a key work in the process of starting a car?'" I'd think people would learn something from that as well.
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I did. It wasn't Why do they need one vs. not needing one. It was a lot more in depth than that. It actually told you WHY it needed one, not just that it did.

I can see why it got that response, though. Too many 'journalists' putting out the tiny basics and no detail and articles that sound like Soapbox threads.
 
My Sprint S3 with 4G LTE does not have a SIM card. Has nothing to do with LTE.
 
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