12.06.24
A SIM — Subscriber Identity Module — is key to using your cell phone. Your SIM stores information about your phone plan that carriers check before granting you access to call, text or use data on their cellular network.
Just like phones, SIM cards have gotten smaller and sleeker over time. And their evolution continues with eSIMs, which are built into the phone rather than existing on a removable card.
Here’s a look at the different types of SIM cards, what’s stored on a SIM card and how to know what type of SIM card you have.
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Different types of SIM cards
Physical SIM cards include a chip, and while the overall size of the SIM card has shrunk over the years, the size of that chip has stayed the same while the material surrounding it slimmed down.
Standard SIM
The oldest type of SIM card, introduced in 1991, is also the largest. It was about the size of a credit card — and most of that was devoted to the plastic surrounding the chip. Users had to open the entire back of the phone or remove the battery to install a standard SIM. These are no longer used in wireless devices.
Mini SIM
These smaller SIMs arrived in 1996 and trimmed away most of the plastic holding the chip. For a while, it was common for SIMs to come in a standard size with perforations in the plastic so the user could break out the smaller mini size if their device called for it. The mini eventually became the go-to size and people started to call it a “standard SIM.” Definitely confusing, but no worries — these first two types of SIM cards are largely out of use now.
Micro SIM
In 2010, the plastic surrounding the chip got even smaller with micro SIMs. As smartphones piled on functionality, a smaller SIM gave more room for other components. These are the more familiar types of SIM, which you insert in a pop-out SIM tray. The iPhone 4 was the first to use micro SIMS, and a few older smartphones still use them.
Nano SIM
Just two years and one iPhone model later, the smallest SIM card came along in 2012. The nano SIM is the smallest removable card, with only a minimal rim of plastic holding the chip. The iPhone 5 was the first to use them, but they're now the most common physical SIM cards in phones and tablets. Nano SIMs also show up in smart watches and other wearables.
Type of SIM
Size
Standard 85.6 x 53.98 mm (3.37 x 2.125 inches)
Mini 25 x 15 mm (0.98 x .059 inches)
Micro 15 x 12 mm (0.59 x 0.47 inches)
Nano 12.3 x 8.8 mm (0.48 x 0.35 inches)
The newest type of SIM: eSIM and iSIM
The latest type of SIM card is not a physical card you have to insert but something built into your phone. That makes activating service fast — no need to wait for a SIM to arrive in the mail — and makes switching carriers easy over an internet connection. It also means no worries you will damage the card when inserting or resetting a SIM.
eSIM
The eSIM came along in 2016. The “e” indicates it's embedded in the phone’s motherboard rather than being a removable card. This lets users change their cell provider without swapping a physical card and allows phones to have more than one user profile at once.
The Motorola Razr was the first eSIM-only phone, and iPhones in the U.S. went eSIM-only with the 14. Research company Statista projects 82 percent of smartphones will be eSIM capable by 2030.
iSIM
The integrated SIM, or iSIM, also arrived in 2016. It’s integrated into the device’s System-on-Chip rather than its motherboard. These are more common in wearables and Internet-of-Things devices like smart home appliances.
What is dual SIM?
Dual SIM is a functionality more than a type of SIM card, but you may see it mentioned when shopping for a new phone.
A dual SIM phone supports two SIMs at the same time so you can have two phone numbers or plans on a single device. That’s handy if you want to keep personal and business use separate without having to carry two phones around, or if you want to add a local SIM while traveling abroad to avoid roaming charges.
In the U.S., most dual SIM phones have a physical nano SIM paired with an eSIM or simply two eSIMs. Either way, you are free to have two different phone numbers, two phone plans and even plans from two different carriers on the same phone if you like.
What’s a postpaid SIM versus a prepaid SIM?
This distinction is not about size of the SIM, but rather the type of phone plan you choose. Postpaid SIMs (physical or embedded) are used with postpaid phone plans, where you are billed at the end of the month — and may have a billing surprise if you used more services than your plan allows. Prepaid SIMs support prepaid phone plans, where you pay up front for a certain amount of service and can’t be hit with extra charges.
How to choose the right SIM card
Your choice of SIM card largely comes down to what phone model you want to use, whether you’d like dual SIM capability, and whether a prepaid or postpaid plan is right for you.
Start with that last one first, and choose the right phone plan for you. Then, decide if you’re bringing your own phone — in which case you only need to make sure it’s compatible with your choice of plan — or buying a new one.
If you’re buying a new phone, the real choice is between single or dual SIM capability. Most phones use nano SIM, an eSIM or have dual SIM capability (which can be a mix of physical and eSIM). You might want to go with a dual SIM phone for ease of traveling, or for separating personal and business use. But generally, picking a phone you like, based on all of its features, will settle the SIM choice for you.
What’s stored on my SIM card?
A SIM’s main job is to identify you and your phone, so a carrier knows you’re allowed to use its network. The biggies stored on your SIM card are:
Your phone number, typically, plus country code and local area identity code.
An IMSI, or international mobile subscriber identity, which connects to your carrier’s network and lets it know you have an account.
A PIN for security, and an unblocking code if you get locked out.
Some unique identifiers of the SIM itself, including an authentication key and an integrated ID.
Some information about your plan and carrier, including name, services and their costs, and numbers you can call for help and information.
The Short Message Service Center that handles texts.
What type of SIM card do I have?
Generally, newer iPhones (14 and later) have eSIMs only. Later-model Androids typically use nano SIMs, and most also support eSIM.
To find out what kind of SIM card you have, search by model name online, such as “type of SIM card in Galaxy 8.” You can also search by model name and “dual SIM” to see if your phone supports more than one SIM.
You could also remove your phone’s physical SIM (if it’s mostly chip with very little surrounding plastic, it’s a nano).
Why do I care what type of SIM card I have?
Honestly, you probably don’t in your day-to-day life! But in a couple of instances, it comes into play.
When you’re switching phones or carriers, the new device or carrier may require a different SIM size.
Also, if you’re traveling and want to install a new SIM from a local carrier to avoid roaming charges, you may need to know which size to purchase. However, many times SIMs are sold in “trio SIM” or “multi SIM” format, which includes the three latest sizes. You simply break the correct one out of its perforations after comparing it to the size of your SIM tray.
Of course, if your phone is eSIM-only, knowing that spares you from worrying about buying the right size at all.
Can I put any SIM in my phone?
SIM trays will fit only the size of SIM that model requires, although you can get SIM cutters to skinny down micro SIMs to fit nano slots, or adapters to put a nano in a bigger micro slot. But since most phones use nano SIMs since 2010, you shouldn’t have to mess with all that.
