You have probably heard of inserting your SIM card when activating service with your carrier network, no matter the device. It could be your phone, your tablet, or whatever - it's a useful piece of universal equipment. However, what exactly is a SIM card? Furthermore, since SIM cards are both used by GSM and CDMA networks, what are GSM and CDMA networks? Better yet, which MVNOs are compatible with CDMA SIM cards?
The answers to those questions are the purpose of this article. Within this guide, you'll find information relating to the definition of the SIM card, what carrier networks are compatible with the CDMA network, the differences between GSM and CDMA, and the Internet of Things.
In This Guide
What Is a SIM Card?
So what exactly is a subscriber identity module card? Well, a subscriber identity module (SIM) card is a type of smart card created for mobile devices. This tiny card contains your unique profile - in other words, your identification number, your personal data such as contacts, and more.
This card also helps you connect with your mobile phone service provider, allowing you to be part of its network. It is important to note that operation of your phone with the network will discontinue if you remove the SIM card from the SIM card slot.
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To put it simply, the SIM card provides all the information a mobile network needs. It lets you know who you are and whether or not you have permission to access the network.
Additionally, you should be aware that there are different mobile SIM card sizes. Depending on your cell phone model and the size of the SIM card slot, you may need a standard SIM, micro SIM, or nano SIM card. And just what are the differences between the sizes?
Well, the standard SIM represents the second generation of SIM cards, measuring 25mm x 15mm x 0.76mm. The micro SIM is the third generation of SIM cards, measuring 15mm x 12mm x 0.76mm. Finally, the nano SIM acts as the fourth generation of SIM cards, measuring at 12.3mm x 8.8mm x 0.67mm.
At one point in your life, you'd probably like to bring your own phone when you switch service providers. Well luckily for you, the SIM unlocking process is quite simple. All you need to do is visit your carrier and they will unlock your phone for you!
However, it should be noted that your carrier sometimes won't unlock your phone. When won't they? Well, for instance, you could owe $200 on your phone before you officially own the phone. In that case, the carrier network may not provide you with the unlock code.
GSM and CDMA? What's the Difference?
GSM and CDMA are two different mobile phone technologies. GSM stands for Global System for Mobile Communications. CDMA, on the other hand, stands for Code Division Multiple Access. GSM is more globally accepted compared to CDMA. But the difference lies in the method of radio wave conversion - yes, the same radio waves that your cell phone broadcasts.
With a GSM carrier, the frequency bands are divided so that multiple users use a tower simultaneously. CDMA networks, on the other hand, layer digitized calls over each other and unpack them on the back end thanks to the issuance of sequence codes. So when you think of CDMA, you think of layers. With GSM, you should think of a square divided up into equal bars.
Yet, as far as carriers go, who relies on what technology?
Well, Verizon and Sprint both rely on CDMA technology, while AT&T and T-Mobile networks use GSM technology. So expect GSM SIM cards with AT&T and T-Mobile networks, but CDMA SIM cards with Verizon and Sprint for your CDMA phone.
You'll notice that when you bring your own phone to a GSM network that you'll need a GSM phone. So be sure to check whether or not you have a GSM phone or CDMA phone with the carrier's official network compatibility page.
Which MVNOs are Compatible with the CDMA Network?
Below, you'll find a list of the MVNOs that are compatible with the CDMA carrier LTE network.
There are tons of CDMA compatible MVNOs, but the above list are some of our favorites. Check them out for our in-depth reviews and find a great cell phone plan that fits your budget.
Internet of Things
More and more devices are now being connected to each other. For instance, your iPhone is connected to your Apple Watch, exchanging information. Or perhaps your car is tied to your Android device. This is commonplace in the modern world. This is also known as the Internet of Things.
The Internet of things is the inter-networking of physical devices, vehicles, buildings and other items embedded with electronics, software, sensors, actuators, and network connectivity which enable these objects to collect and exchange data.
Let's refer to this example: your smartwatch and your smartphone. To put it simply, your smartwatch - say the Samsung Gear S2 - is tied to your smartphone. Not only does your smartwatch show you notifications like text messages, the weather and more, but it can help record your activity, which can be relayed to your smartphone.
Of course, there are many more devices that are integrated with each other. Another relevant example is SIM cards. Nowadays, they are not only used in mobile phones but also inside GPS trackers, smartwatches, tablets, and more. Overall, you should be aware that your SIM card is a valuable piece of plastic, containing your unique identity within these items. While losing the SIM card isn't as detrimental as losing your social security card, it still is an important tool.
Not only that but there are some carrier networks, like US Mobile and TPO Mobile, that offer SIM cards specifically for non-smartphones.
As you can tell, there are plenty of mobile providers that rely on CDMA technology. Otherwise, you'll likely find yourself purchasing either an unlocked phone from a retailer or directly from the official carrier website, which can be expensive.
SIM cards are useful for giving a data plan to a plethora of devices such as activity trackers, alarm systems, smart watches, and more. For more information, reviews, and comparisons check out our connected devices directory.
Need GSM SIM cards instead? Go here.