The iPhone XS, Max, and XR are the first Apple phones to include Dual Sim technology. For the iPhone XS and XR, this involves having an eSim as well as a physical sim card slot. This is not unlike the current generations of Google Pixel (Pixel 1 and 2), but the iPhone can have both the eSim and physical sim active at the same time. With the iPhone XS Max, the sim card slot is essentially double-sided, enabling support for 2 physical sim cards.
Now that I have this shiny new Dual-SIM-eSIM phone in my hands, I wanted to test out support for Verizon combined with Google Fi (the ultimate service combo!)… Apple, however, will not support the eSIM technology until November 2018 when they will release an app (or settings feature) which will enable setup of the eSIM.
Of course – SIM is not an Apple technology.
SIM is the “Subscriber Identity Module” in a GSM terminal, all terminals must have a SIM to register on a HLR/VLR. And you have to register on at least a VLR for another HLR, or directly with an HLR to be provided roaming. The SIM is where your mobile subscription is confirmed, your mobile number “MSISDN” and your handset – iPhone, that contains the “IMEI”.
Your operator – (US:”Carrier”) will check the IMEI to see if the handset is “free to be used” against a database of stole phones, everywhere in the world. They can also track you, that you have paid all outstanding invoices, or if you have issues with another, be warned before taking you on. They will see what your handset (IMEI) is capable of, and upload and install software drivers needed to make the best use of the network. This is done on the GSM backbone network – not on “internet” as 4G, but more or less as a burst of SMS messages. They can also download and install character sets – the phone do not use UTF8 character code, but ITU t.56 which is “everything” also graphics.
Verizon use CDMA and this do not use a SIM. They sell SIM in the US because the phones are dual network phones that use the GSM network when abroad, and can also use the GSM for data access: when you surf the net, this may be faster and cheaper on the GSM network, and you are carried over to this. Who cares – in the end, the network owners get paid, they charge per packet use. The SIM is also the clue to an openess the Americans have not discovered yet: anyone can make their own subnet of the mobile GSM network, and the operators can move traffic to subnets as long as this has better signals and preferred prices. You can start at home, need not national coverage, just negotiate with AT&T, get a license for “your area” apply for radio frequencies and be awarded – roll out and charge AT&T – they will pay. But you will then have your own “VLR” that AT&T uses and you manage as the main switch in your network. They you will have your own “CIC” and can issue your own SIM that contains just what you want them to contain. Apple will have to use them – they just manufacture devices and cannot make mobile telecommunication standards – that is for the GSM and the members in the ITU – where the FCC does not even vote. It is the network companies like Nokia/Siemens, Ericsson, Huawei, ZTE and Samsung that can propose new technology and get it approved and used by the GSM consortium. Now, these “carry” proposals for US companies and speak on behalf of them because of the policy to the FCC. The FCC has wasted US taxpayers moneys on the CDMA technology that I and others have know from the start would fail – they ignored an error / mistake in the math. Well lots of money can get you far, but defy math, requires more.