We live in the age of technology, and one of the most ubiquitous technologies we experience every day is cellular phone technology. These wireless phones connect us to the far reaches of the world. The basic structure of a cellular phone network consists of many base stations that cover a certain area. Mobile phones use these base stations to make calls, send texts, and access the internet. These base stations are assigned multiple radio frequency bands for communication. The number of frequency bands that can be used for communication is limited, and they are considered valuable resources.
In order to reuse frequency bands and allocate them to many cell phone subscribers, mobile phone network operators adopt multiple access schemes. These schemes are used to distinguish signals from several different transmitters covered by a single base station and to squeeze multiple phone calls or internet connections into one radio channel. CDMA and GSM are two such methods that are widely adopted by carrier companies. These technologies are critical for end users when purchasing a new smartphone or switching carriers.
What is GSM?
The Global System for Mobile Communications (GSM) is a standard for digital cellular networks that was developed by the European Telecommunications Standards Institute (ETSI). It is the most widely used mobile phone standard in the world, and is used in over 220 countries.
GSM networks use a time-division multiple access (TDMA) scheme to divide the available radio spectrum into time slots, which are then allocated to different users. This allows multiple users to share the same frequency band without interfering with each other.
GSM networks also use a digital modulation scheme called Gaussian minimum-shift keying (GMSK) to improve signal quality and reduce interference.
GSM networks typically operate in the 900 MHz or 1800 MHz bands, although some networks also operate in the 850 MHz or 1900 MHz bands.
The GSM standard has evolved over time, and there are now several different versions of the standard in use. The latest version is GSM 1900, which supports data rates of up to 2 Mbps.
Operation
When you make a phone call, your voice is converted into digital data and placed in a single radio channel. This channel is then transmitted to the nearest base station. Your data and other signals are packed together in time slots, and the receiver on the other end listens only to the assigned time slot to reconstruct your call.
To connect to a GSM network, you need a billing type (prepaid or postpaid), a subscriber identity module (SIM card), and a mobile device compatible with GSM. When the SIM card is activated for the first time, the billing relationship is established and the phone number, also known as the Mobile Subscriber Integrated Services Digital Network Number (MSISDN), is programmed by the subscriber.
The SIM card is tied to the network rather than the phone. This allows phones to be instantly activated, interchanged, swapped out, and upgraded without carrier intervention. The SIM card has its own memory, known as the HLR (Home Location Register), which stores billing information, contact numbers, type of service available, and other information.
What is CDMA?
CDMA is a way for multiple people to talk on the phone at the same time without interfering with each other. It was first developed in the Soviet Union in 1957, and it’s now used in all sorts of wireless technologies, like cell phones and GPS.
There are two main types of CDMA: synchronous and asynchronous. Synchronous CDMA uses codes that are all in sync with each other, while asynchronous CDMA uses codes that are randomly generated. CDMA is more efficient than other multiple access technologies, like FDMA and TDMA, because it allows more people to use the same frequency band at the same time.
CDMA is also more resistant to interference than other technologies. This is because each user’s signal is spread out over a wide range of frequencies, so it’s harder for other signals to interfere with it.
CDMA is a pretty cool technology, and it’s one of the reasons why we have such great wireless communications today.
Operation
CDMA is a multiple-access technique that allows multiple users to share a network simultaneously without interfering with each other. Voice or data is converted into digital signals and mixed with unique codes before being transmitted. The base station separates the signals and routes them to the correct destination. The receiver extracts the desired signal using the code.
CDMA is a more efficient way to use a wireless network than other multiple-access techniques, such as FDMA and TDMA, because it allows users to share the same frequency band without interfering with each other. This makes it possible for more users to connect to a wireless network at the same time.
CDMA is also a more reliable way to transmit data than other multiple-access techniques because it is less susceptible to interference from other signals. This makes it a good choice for applications where reliable data transmission is important, such as voice and data communications.
CDMA is a widely used multiple-access technique. It is used in many wireless networks, including cellular networks, satellite networks, and Wi-Fi networks.
Will GSM Phones Work on CDMA Networks and Vice Versa
In general, no. As explained earlier, GSM and CDMA phones have some fundamental differences in their technology, and you will not be able to get service if you try to use a GSM phone on a CDMA network or vice versa. Additionally, some GSM carriers provide carrier-locked phones that are not compatible with other GSM networks. These phones can sometimes be unlocked, but this is not always possible. However, there are some recently developed devices such as the iPhone 8b or 8 Plus, Google Nexus, and Galaxy S20 that are compatible with all three major cellular technologies: GSM, CDMA, and LTE.
GSM vs CDMA: Main Differences
GSM and CDMA are two different types of cellular networks. To explain the main difference between them, let us consider a simple analogy. Imagine a room full of people who want to talk to each other. If everyone starts talking at the same time, no one will be able to hear anything. To avoid confusion, there are several techniques that can be used, such as:
- People could take turns speaking (time division multiple access, or TDMA).
- People could speak at different pitches (frequency division multiple access, or FDMA).
- People could speak in different languages (code division multiple access, or CDMA).
CDMA is a more efficient way of using the available frequency spectrum than TDMA or FDMA. This is because CDMA allows multiple users to share the same frequency band at the same time, without interfering with each other.
Some other aspects of GSM and CDMA that customers should consider include:
- Connectivity: GSM phones use SIM cards to connect to the network, while CDMA phones do not. This means that if you want to change your GSM phone, you can simply insert your SIM card into a new phone. However, if you want to change your CDMA phone, you will need to contact your service provider and have them deactivate your old phone before you can activate your new one.
- Network coverage: GSM is the more widely used standard, with coverage in over 193 countries and territories. CDMA is more popular in North America, Japan, and some other parts of the world.
- Call quality: CDMA is generally considered to have better call quality than GSM. This is because CDMA is less susceptible to interference from other signals.
CDMA vs GSM: Comparison Chart:
| Feature | CDMA | GSM |
| Technology | Code Division Multiple Access | Global System for Mobile Communications |
| Developed by | Qualcomm | European Telecommunications Standards Institute (ETSI) |
| Popularity | More popular in North America, Japan, and some other parts of the world | More widely used standard, with coverage in over 193 countries and territories |
| Connectivity | Phones do not use SIM cards | Phones use SIM cards |
| Network coverage | Less widespread | More widespread |
| Call quality | Generally considered to have better call quality | Generally considered to have lower call quality |
| Security | Better security against eavesdropping | Less secure against eavesdropping |
| Battery life | Shorter battery life | Longer battery life |
| International roaming | Not possible with all carriers | Possible with all carriers |
| Switching phones or service providers | More difficult | Easier |
| SIM backup options | Not available | Available with some carriers |
Ultimately, the best type of cellular network for you will depend on your individual needs and preferences. If you travel frequently, GSM may be the better option because of its wider coverage. If you are concerned about call quality, CDMA may be a better choice.
Which One is Better GSM Or CDMA?
With the advancement of network technologies, the distinction between GSM and CDMA is becoming increasingly blurred. 3G GSM is essentially CDMA technology with a SIM card, and the actual name of this technology is Wideband Code Division Multiple Access (WCDMA). Service providers that use WCDMA also have their older GSM network activated. The question of which is better, GSM or CDMA, is not a technical one; it is more of a marketing issue.
However, earlier versions of GSM and CDMA had their own advantages and disadvantages. For example, CDMA has a lower risk of crosstalk and better security against eavesdropping than GSM. CDMA technology can also accommodate more callers at the same time with the same amount of bandwidth as GSM. If your phone is lost or stolen, CDMA operators store your phone book on their database.
GSM phones have lower power consumption and hence longer battery life than CDMA phones. Additionally, GSM networks are available worldwide, and international roaming is possible with these operators. Furthermore, it is quite simple to switch phones or service providers with GSM technology; all you need to do is change your phone and insert the SIM card, or change the SIM card when you change carriers. Recently, GSM service providers have begun offering SIM backup options to protect your personal information and contacts.
Lists of CDMA and GSM Carriers (USA)
The United States is home to a wide variety of network operators, each with its own unique infrastructure and services. Some operators own their own networks, while others lease networks from other companies. These latter operators are known as mobile virtual network operators (MVNOs). MVNOs typically have more flexibility than traditional carriers, as they can lease networks from multiple companies and offer a wider range of services.
The following is a list of network operators in the United States that use GSM or CDMA technologies:
CDMA operators:
- Verizon Wireless
- U.S. Cellular
- Sprint
- Alaska Communications
- Appalachian Wireless
- Blue Wireless
- Bluegrass Cellular
- Bravado Wireless
- C Spire Wireless
- Carolina West Wireless
- Cellcom
- Chariton Valley Wireless
- Chat Mobility
- Choice Wireless
- Clear Talk
- Copper Valley Telecom
- Custer Telephone Cooperative
- ETC (Enhanced Telecommunication Corporation)
- GCI Wireless (maintains a CDMA and GSM network; contact provider for more information)
- Illinois Valley Cellular
- Inland Cellular
- Mid-Rivers Communications
- Mobi PCS
- MTA Solutions
- Nemont
- Nex-Tech Wireless
- NorthwestCell
- nTelos
- Pioneer Cellular
- Silver Star Communications
- Sprocket Wireless
- STRATA Networks
- Thumb Cellular
- United Wireless
- Virgin Mobile USA
GSM operators:
- AT&T
- T-Mobile
- ASTAC
- Metro by T-Mobile
- Mint Mobile
- Google Fi
- Big Sky Mobile
- Cellular One Nation
- Cordova Wireless
- Cricket Wireless
- DTC Wireless
- Visible
- Xfinity Mobile
- Republic Wireless
- GCI Wireless (maintains a GSM and CDMA network; contact provider for more information)
- Indigo Wireless
- Tello
- Pine Cellular
- Plateau Wireless
- Union Wireless
- Boost Mobile
- Tracfone
- Straight Talk Wireless
- Net10 Wireless
- H2O Wireless
- Page Plus Cellular
- West Central Wireless
How to Check CDMA or GSM
If you are unsure whether a phone is GSM or CDMA compatible, here are some tips:
- Check for a SIM card slot. A conventional GSM phone will have a dedicated SIM card slot, typically located on the side or back of the device. Modern 4G LTE smartphones are CDMA compatible and may also have a SIM card slot. However, if your phone does not have a SIM card slot, it is definitely a CDMA phone.
- Check with your carrier. If you purchased your phone directly from a carrier, they should be able to tell you which network technology your phone is compatible with. Note that Verizon uses CDMA technology, but they also sell phones that are compatible with both GSM and CDMA networks. AT&T and T-Mobile are GSM network operators, and they offer GSM devices. Sprint is a CDMA carrier company.
- Check your phone’s settings. You can also check your phone’s settings to determine its network compatibility. For iPhone, go to Settings > General > About and look for an MEID, ESN, or IMEI number near the bottom of the menu. Phones with MEID or ESN numbers are CDMA devices, while phones with IMEI numbers are GSM phones. For Android phones, go to Settings > System > About phone and look for the Status icon. Tap on it and look for an MEID, ESN, or IMEI number.
- Search for your phone’s model number online. Finally, you can also search for your phone’s model number online to find out its network compatibility. Almost every major manufacturer and service provider has their own website that contains information about their devices. There are also third-party websites that showcase customer reviews and technical details, which can be valuable resources.
GSM vs CDMA: The Future
As the requirements for high-quality voice calls, video calls, high-speed internet connections, and multimedia messaging skyrocket day by day, networking technologies are constantly evolving. Engineers and technologists are always striving to provide better services and eliminate existing problems. As a result, networking standards and other services are always changing.
As mobile networks enter the 4G era, the distinction between GSM and CDMA is becoming increasingly blurred. LTE technologies are attempting to combine the features of both GSM and CDMA. In the future, new technologies like 5G networks will be implemented, making the choice between GSM and CDMA even less relevant.
However, for 2G and 3G networks, GSM and CDMA handsets will never be interchangeable. For local use, both GSM and CDMA work well for voice calls and 3G data services. As a result, for the time being, you must check the device’s compatibility with GSM or CDMA, which will no longer be necessary in the future.
