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Thread: New iPhone, new or old (also iPhone) SIM

  1. #1
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    New iPhone, new or old (also iPhone) SIM

    I purchased new iPhone 12 models for me and my wife. They included a SIM. We each had iPhone 7 models.

    Before T-Mobile sent a message with "how to upgrade" instructions, I used Apple's instructions. Apple said to remove the SIM from the old phone and put it in the new phone before doing migration. I followed these instructions. All __APPEARS__ to be working well.

    T-Mobile said complete the migration, then use either their app or website to activate the new SIM. My wife followed these instructions; she had a minor problem and contacted tech support. I had her ask why they and Apple differ, and that her husband used the old SIM.

    They said that the new SIM had greater capabilities than the old, and that I should switch and activate for "new software".

    Color me STUPID. I didn't think there was any reason to replace a working SIM.

    Please, some knowledgeable person (trolls and opinions are not solicited, knowledge only) tell me __IF__ & __WHY__ I should change the working SIM. What kind of new capabilities could be involved.

    Thanks!

    George

  2. #2
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    The new sims work with tmobiles 5G SA network. There have been reports of older sims also working with it, but, they recommend using the new R15 sims for 5G. There is absolutely no negative to using the new sim over the old one.

  3. #3
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    Quote Originally Posted by gbynum View Post
    … tell me __IF__ & __WHY__ I should change the working SIM…
    George, just like anything in technology, it moves very fast. USIM sim cards are the standard from 2g to LTE, they have the capabilities to store encrypted certificates for towers, user subscription, carrier code.. etc … sim cards support the basic 32, 64 and 128 bit for LTE.. (this is why newer cards sometimes dont function in older phones) 5G uses 256 bit encryption making the older 128 bit absolete… it is true that changing sim cards will fix signal because now you have such certificates to connect to a new tower or an updated tower.
    The R15 sim card supports stand alone 5G, something that t-mobile already uses.
    You use an iphone, from time to time you will see the famous “carrier update” ; this updates your iphone and your sim card with new certificates, prioritize connectivity, new towers, new partners, or delete partners (like sprint towers) or add new capabilities like wifi calling.
    Of course, is up to you if you want to update

  4. #4
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    Quote Originally Posted by cr0w View Post
    The R15 sim card supports ...
    Thanks!

    I ***_U ME, the ***_ applying exclusively to ME, that the R15 is Rev 15; how can the rev levels be identified? For example, the SIM (older) in my 12mini (from the screen) is 8901 2602 3570 7014 xxx.

    The new one, printed on it, is 8901 2602 8670 8641 xxx. This one also has, in red, R15. I don't recall (never looked truthfully) what is marked on the installed one.

    (I replaced the final 3 digits with xxx in case there might be some crooked reason for someone to know it.)

    George

  5. #5
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    Quote Originally Posted by gbynum View Post
    Thanks!
    ...how can the rev levels be identified?...
    The previous LTE sim card was revision 9263, 9264 which is believed that it supports 5g stand alone... but wont you rather go with the R15? there is also an R12 but ... nah, go with the newest.

    sim card numbers are like credit cards... all their numbers are randomized, except for the group 8901-26 thats t-mobile.. all other numbers are totally random.. some are high, some are low.
    you have the 12 mini.. you can also go e-sim if you wish..

  6. #6
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    Thanks! I'll swap in the next few days.

    My issue was that Apple's instructions said to install the existing SIM which worked; it wasn't until TMo sent their instructions that I knew there was an option. It wasn't until your help that I realized there might be a PREFERABLE option.

    I'm aware of the 12 series supporting dual SIMs, one of which must be an e-SIM if dual; does anyone (curiosity only) support 2 physical SIMs? I think that phonescoop will answer that.

    I appreciate the info. Back in the MTS and IMTS days, I worked in the engineering department for a company who made mobile phones; things have changed more than just a little.

    Thanks for your help!

  7. #7
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    Dual Physical SIMs are supported on only a few newer phones now as eSIM is becoming more prevalent.

    The iPhone 12 sold in China, Hong Kong and Macao are dual physical SIM, but doesn’t support all of the same bands as the US version (and some other features aren’t supported like WiFi calling).

  8. #8
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    Put the R15 SIM in and activated. Thanks for all the help!

  9. #9
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    Quote Originally Posted by high technology View Post
    ...like WiFi calling ...
    and the app store is limited... and the camera always makes that shutter sound no matter if silent... Chinese really care about their privacy... (insert sarcastic laugh here)

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