GSM VS CDMA Phone Networks: What's the Difference and Which One is Better?

By Carrie Tsai,  Last Updated: August 28, 2019

If you want to buy a new phone and choose a carrier, or you are just interested in the mobile network, you may have heard of GSM and CDMA. But what are they on earth and how will they affect your life?

What is GSM and CDMA

CDMA is the abbreviation of Code Multiple Access, which is a wireless communication technology developed on the branch of digital technology-spread spectrum communication technology. While GSM represents Global System for Mobile Communication, which is one of the world’s major cellular systems.

There lies a great gap between this two basic technologies in mobile phones. They are the reason why you can not use your old AT&T phone on the Verizon network, and vice versa.

The Carriers of GSM and CDMA

In the US, Sprint, Verizon and US Cellular use CDMA while AT&T and T-Mobile are GSM carriers. GSM is used in most of the countries in the world. The global spread of GSM is the result of mandatory technology required by European law in 1987. GSM was from an industry consortium.

On the other hand, the so-called CDMA is mainly owned by Qualcomm, a chip maker giant. Carriers can choose from many variants and options, the equivalent of the toppings on the ice cream. This article will generally focus on the US network.

The Technology Behind CDMA and GSM

Both CDMA and GSM take in the technology of multiple access, by which people can plug multiple phones or internet connections into one radio channel.

GSM ranked the first, which is a “time division” system. Your voice will be converted into digital data and will give a channel and time slot, therefore three calls on one channel will look like 123123123. On the other hand, the receiver only listens to the specified time slot and the call will be divided into two parts.

The pulse of the time-division signal generated the notorious GSM hum, which made a squeak every time you put your phone close to speaker. But nowadays, most of it has gone due to 3G GSM, which do not use the time-division technology.

On the other hand, CDMA demands of more processing power because this is a “code-division” system. The data of each call is encoded with a unique key and the call will be transmitted all at once.

For instance, if 1, 2, and 3 calls are in one channel, the channel will only say 666666666. And every receiver will has only one suitable key, which is used to “divide” the combined signals into their respective calls.

Since the code division is a more powerful and flexible technology, the 3G GSM is in fact a CDMA technology called WCDMA (Wideband CDMA) or UMTS(Universal Mobile Phone System). As the name implies, WCDMA requires a wider channel than the old one while it will has bigger data capacity.

What Does CDMA and GSM Mean to You

In the prospect of calling quality, the technology behind is way less important than how carriers build their networks. Both CDMA and GSM is doubled-edged sword. However, there is still technological difference in them. Here is what you need to know as a consumer.

First and foremost, it is much easier to exchange cell phone in GSM since carriers place customer information into a removable SIM card so that the new phone will have your original phone number.

More importantly, carriers must accept any handset that complies with the GSM standard. Therefore, they can not take the control of the mobile phone you are using completely.

However, that is not the case with CDMA. In the US, CDMA carriers use a network-based whitelist to authenticate their users, which means that you can only switch to a new phone under the approval of carriers. In addition, carriers do not have to accept any specific calls on their network and they often choose not to do so.

Which is Better

GSM and CDMA are different ways to accomplish the same goal. The fact that extremely popular networks are built on each simply proves that it’s the quality of the network, not the standard, which is important. For instance, in the United States, two of the four major carriers (Verizon and Sprint) use CDMA while the other two (AT&T and T-Mobile) use GSM.

Technically, neither is the better in terms of quality, but there are some things here for your consideration. GSM phones are able to be unlocked and moved between carriers, but CDMA phones are often locked to a single carrier and unable to be transferred.

The Future of CDMA and GSM

You had better not buy 2G GSM phone in the US since US carriers are moving away from CDMA and 2G GSM, which will result in some old dumb phone or foreign phones stopping working in the US.

These 1990s technologies are usually cheap to buy and put into use and are inefficient users of radio waves. As we try to spread more and more data into the air, carriers are shifting their channels from old technologies to more efficient 4G and 5G systems which can have more users and data packed into the channels of the same size.

The representative of LTE(Long-Term Evolution) is widely spreading, thus leading an evolution of GSM and it uses technology similar to the GSM networks. The standard improves the voice quality and serves as the basis for high-speed 4G data networks.

In this sense, LTE does lead the competition in terms of overall speed and quality. The next step which will provide further improvement is 5G technology, which is underway. And it is believed that our digital live will be unprecedentedly convenient.