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What is CDMA SIM Card?

CDMA SIM Card

Bombarded with advertisements for CDMA SIM cards? There’s no point in buying anything unless you understand how it can benefit you. And although compulsive shoppers and those upsold by their carrier beg to differ, we know you’re better than that. After all, you’re reading this article. Don’t fret, we’ll tell you all you need to know about CDMA SIM cards. But if we’re being honest, you don’t have to retain this information for too long – the term likely won’t exist for much longer. Let us explain. Here’s an answer to the question, “what is a CDMA SIM card?”

What is CDMA?

To help you understand CDMA SIM cards, you should understand the base term. CDMA (Code Division Multiple Access) is a radio telecommunication standard patented by Qualcomm. It grants users on the network access to an entire spectrum of radio bands. All calls are encoded with a unique key, transmitted concurrently, and codes are divided at the network receiver. This increases the number of simultaneous users on the network. However, CDMA is limited to 2G and 3G network functionality/capability.

CDMA drawbacks

This will show you why CDMA SIM cards are so popular. These are the 4 main cons of CDMA:

  1. The standard is patented. For that reason, it is only used by between 10% and 20% of the world, and the number is dropping.
  2. CDMA uses the phone itself to identify the user. Unlike GSM, which uses SIM cards, carriers must program their devices to use CDMA. Every device is added to the network white-list, allowing it to identify itself. That also means you must buy a new phone when switching carriers.
  3. Network coverage is low. We explain this in detail below. It might not matter in your home country, but will be of great significance with international roaming. You’ll struggle to find CDMA networks, and you can’t buy a local SIM card to avoid roaming fees and get short-term package deals.
  4. CDMA 2G/3G cannot transmit voice calls and mobile data simultaneously. This wasn’t a big deal in the past, but nowadays it certainly is.

Where are CDMA SIM cards used?

When it was first introduced, some carriers decided to build GSM network infrastructure, while others chose CDMA. Because it’d be extremely expensive to switch to another standard after decades of investing, they continue using it. CDMA SIM cards are used wherever there are carriers that use CDMA infrastructure. In the United States, CDMA SIM cards are used by Verizon, Sprint, and US Cellular. CDMA SIM cards are also popular with some Russian carriers.

Why are CDMA SIM cards sold?

We understand your confusion. After all, CDMA phones don’t use SIM cards for user authentication. That remains true when you look at CDMA alone. The reason CDMA SIM cards are sold and used is the popularity of 4G and 5G LTE network technology, which makes 2G and 3G obsolete. This forced carriers to start implementing SIM card slots into their CDMA devices to service LTE networks. That’s why you’ll see the term “CDMA LTE” when buying a smartphone.

To summarize, CDMA SIM cards add 4G and/or 5G LTE network functionality to CDMA-compatible smartphones. This allows carriers to completely avoid routing data through CDMA for newer smartphones. Besides expanding on functionality and speed, CDMA SIM cards increase network coverage to LTE infrastructure without forcing users to buy LTE-only phones. Simultaneously, users retain the ability to use 2G/3G CDMA infrastructure if they wish or are forced to. Verizon even started adding GSM capabilities to some of its CDMA-compatible phones.

How to check whether the smartphone uses CDMA

To determine whether to buy a CDMA SIM card, the first clue should be the name of your carrier. If you’re still not sure, use software to check whether your smartphone is using CDMA:

iPhone

To check your iPhone communications standard, do this:

  1. Open the Settings app.
  2. Tap on General, then About.
  3. Browse the list for IMEI, ESN, and MEID numbers.

Android

Here’s how to check the communications standard of your Android device:

  1. Tap on the Settings app.
  2. Tap on About phone.
    It might be in System > Status or My phone > All specs > Status.
  3. Take notice of the three numbers again.

Distinguish between CDMA and GSM

Here’s how to tell CDMA and GSM apart:

  • If you see an IMEI number, your smartphone uses GSM.
  • If you see MEID and ESN, it uses CDMA.
  • Saw all 3 numbers? Your smartphone can work on CDMA and GSM using the SIM card slot.