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CDMA versus GSM: What’s the difference?

If you’re in the market for a new phone or cell carrier, or are interested for any reason in cell phone networks, chances are you’ve run into the acronyms CDMA and GSM. You may be wondering what exactly are GSM and CDMA, and how do they affect your phone?

The two cellular standards function in different regions and allow for global communication between individuals, though, each converts incoming and outgoing data into radio waves differently. Neither should be a huge factor when buying a cell phone, but one standard is notorious for tethering you to a carrier while the other is not. It all depends on where you are and what you’re looking for.

Related: LTE Advanced explained | What is the difference between 4G and LTE?

GSM Explained

The iPhone 6 is a smartphone that typically functions on a GSM network.

The iPhone 6 is a smartphone that typically functions on a GSM network.

GSM stands for Global System for Mobile Communication, and unless you live in the United States or Russia, this is probably the technology your phone network uses, given it’s the standard system for most of the world. GSM networks use TDMA, which stands for Time Division Multiple Access. TDMA works by assigning time slots to multiple conversation streams, alternating them in sequence and switching between each conversation at very short intervals. During that interval, the phones can transmit their information. In order for the network to know which users are connected to the network, each phone uses a subscriber identification module card, or SIM card.

SIM cards are one of the key features of a GSM network. They house your service subscription, network identification, and address book information. The identification is used to assign time slots to the phone conversation, and moreover, it tells the network what services you have access to, while storing your address book and relative contact information. Said cards can even to pass the information between phones, if a carrier allows it.

CDMA Explained

The Droid Turbo is a smartphone that runs on Verizon's CDMA network.

The Droid Turbo is a smartphone that runs on Verizon’s CDMA network.

CDMA, or Code Division Multiple Access, is commonly found in the aforementioned territories of the United States and Russia — though GSM is also present in those countries as well. The Allied Forces developed the technology during World War II as a method to prevent Nazi forces from jamming radio signals. CDMA, unlike GSM, allows users full access to the entire spectrum of bands, thus allowing more users to connect at any given time. It encodes each user’s individual conversation via a pseudo-randomized digital sequence, meaning the voice data remains protected and filtered so that only those participating in the phone call receive the data.

Phones on CDMA networks do not use SIM cards. Instead, each phone is built specifically to work on that carrier’s network. What does this mean for consumers? For starters, it means that phones are tied to a carrier and their bands, so if you decide to change cell phone companies, you’ll have to buy a new phone.

Is One Better Than The Other?

Not necessarily. Both are the global standards for cell communication. The major factor affecting call quality is the network itself, rather than the method it uses to transmit information. Of course, there are some things to keep in mind when it comes to choosing between CDMA and GSM phones. For starters, CDMA phones are tied to their carriers, and cannot be transferred to other networks. For example, a Verizon phone could not be transferred to Sprint’s network, and vice versa. In contrast, GSM phones can be jailbroken and transferred to other networks. Additionally, third-party manufacturers often sell phones designed for GSM networks since they do not require access to a specific carrier’s bands. GSM phones will also work in other countries with compatible GSM networks.

That said, CDMA networks do allow for a greater number of users, meaning their capacity for communication is greater than that of GSM networks. On top of that, CDMA is the infrastructure on which all 3G networks are based — for both GSM and CDMA carriers. However, now there’s a third type of network that is quickly becoming the front runner in terms of quality, with many major cell phone companies quickly adopting it. Appropriately dubbed LTE for Long-Term Evolution, the technology is an evolved form of GSM and uses a similar technology as GSM networks. The new standard boasts enhanced voice quality, and furthermore, functions as the base of high-speed, 4G data networks. In this case, LTE does have an edge over the competition in terms of overall speed and quality.

If you’re a U.S. customer and wondering what companies use which type of network, the split is right down the middle: AT&T and T-Mobile are GSM carriers, while Verizon and Sprint are CDMA. In truth, picking a new phone or carrier solely based on GSM, CDMA, or LTE doesn’t necessarily matter, as what services, features, phones, and service quality a network offers aren’t solely dependent on their network infrastructure. So, unless you have a particular need for choosing one of the other, go with the carrier that best fits your tastes, needs, and budget.