Apple unveiled the iPhone Xs and Xs Max yesterday and revealed that both phones support dual SIM capabilities, a first for iPhone.
Most readers are aware that any mobile phone requires a SIM (Subscriber Identification Module) card to connect to the mobile network. A phone that can hold two different SIM cards at the same time is called a Dual SIM device. Having two SIM cards means that a Dual SIM smartphone can use either of the two SIMS to initiate or to receive phone calls, text messages etc.
For many users, having a Dual SIM smartphone can be extremely useful. For instance, businessmen and women who tend to have one phone number for their work and another number for their personal contacts. A business person can either use two different smartphones, one for work and one for personal use, or use a Dual SIM smartphone, with both phone numbers active on it. Having one smartphone to carry around is easier than carrying two smartphones.
Another situation in which you might be interested in a Dual SIM smartphone is when you want to use one phone number for phone calls, and the other for connecting to the internet. There are mobile operators that have good voice plans, but costly data plans, or the other way around. On a Dual SIM smartphone, you can combine two different plans from two different operators and get a cheaper bill at the end of the month.
Another benefit is that you can use two mobile providers simultaneously if your phone is not locked into a specific network. This means that you can get more mobile coverage. If you travel a lot abroad, you can use one SIM card in your home country and the other SIM slot for cards you purchase in the countries you travel to, for better or cheaper coverage.
There are variations of physical dual SIM implementations and I won’t go into the technical details of that here, but the one common factor they have is they allow two physical sim cards in the phone. Not all Dual SIM devices work the same, and some Dual SIM implementations are better than others.
iPhone Xs and iPhone Xs Max Dual SIM
Apple doesn’t implement physical dual SIM technology but instead they have opted for one physical sim (as normal) and one eSIM. Just like on the iPad, you’ll have to subscribe to a plan. An eSIM is a digital SIM that allows you to activate a cellular plan from your carrier without having to use a physical nano-SIM – and the difference is huge.
For instance, at the time of writing, this limits the usage in the UK to EE and Vodafone.
Apple systems use Dual SIM Dual Standby, which lets you make and receive calls on both lines. Note though that if one number is on a call, incoming calls on the other number will go to voicemail. Also, if you are active on a voice number that isn’t your designated data number, data will not work while your are on the call.
As with other Dual SIM solutions on the market, Apple lets you label each SIM card, as well as choose a default line. The secondary line can be used for data only – a handy option if you’re traveling and pick up a local SIM just for that purpose.
For each contact you call the iPhone will choose the same number you used last time. If you haven’t called before, then your default number will be used. Yet if you want you can specify which subscription to use for a specific contact.
Of course, it should also be highlighted that to use different carriers on each sim, your iPhone would need to be an unlocked model.
Interestingly, in China, Hong Kong and Macau, Apple can’t embed an eSIM into its devices. So the company is going to release a special iPhone XS and XS Max for China. This model will let you insert two physical SIM cards at once, back-to-back. Definitely a preferable solution until all carriers support eSIM technology.