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GSM vs. CDMA — What's the Difference?

By Tayyaba Rehman — Published on January 9, 2024
GSM uses a SIM card for identifying subscribers and operates on a time division multiplexing system, while CDMA embeds subscriber information in the phone and uses a code division technique.
GSM vs. CDMA — What's the Difference?

Difference Between GSM and CDMA


Key Differences

GSM (Global System for Mobile Communications), a standard developed by the European Telecommunications Standards Institute, uses a SIM card to identify subscribers on the network, allowing for easy handset switching. CDMA (Code Division Multiple Access), developed by Qualcomm in the United States, ties the subscriber's identity to the handset itself, making switching devices more complicated.
GSM networks operate using a time division multiplexing system, where multiple calls are divided into time slots. CDMA uses a code division technique, where each call is encoded with a unique key, allowing multiple calls to overlap in time and frequency.
In terms of global coverage, GSM networks are more widespread, offering better international roaming capabilities. CDMA, although used in various countries, has a smaller global footprint compared to GSM.
GSM's SIM card-based system provides more flexibility for users to change phones or carriers. CDMA phones, without a SIM card, typically require carrier intervention to change or activate on another network.
GSM technology tends to have more frequent handovers from one cell tower to another, which can be a disadvantage in areas with less dense network coverage. CDMA's spread-spectrum technology generally provides better coverage in such areas.

Comparison Chart

Subscriber Identification

Uses SIM cards.
Tied to the handset.


Time Division Multiplexing.
Code Division Multiple Access.

Global Reach

Widespread global coverage.
Limited compared to GSM.


Easy to switch phones and carriers.
Requires carrier intervention for changes.

Network Coverage

Better in densely populated areas.
Better in areas with sparse coverage.

Compare with Definitions


GSM operates on a time-division multiplexing system for call handling.
GSM networks efficiently handle multiple calls through allocated time slots.


CDMA is a mobile technology where each call uses a unique code for access.
My CDMA phone's call quality is maintained by using a distinct code for transmission.


GSM phones offer easy handset switching due to the use of SIM cards.
Switching to a new phone was simple on my GSM network, just by moving the SIM card.


CDMA utilizes spread-spectrum technology for handling calls.
CDMA's spread-spectrum technique provides me with reliable coverage in rural areas.


GSM is widely used globally, offering extensive international roaming.
GSM's global coverage made it convenient for me to stay connected while traveling.


CDMA embeds subscriber information directly into the phone.
Switching my CDMA phone to another carrier required a visit to the service provider.


GSM is a standard for mobile telephony using SIM cards for subscriber identity.
I was able to use my GSM phone easily overseas by swapping the SIM card.


CDMA is known for its efficient use of bandwidth and coverage.
In sparsely populated regions, my CDMA network offers better connectivity than GSM.


GSM technology is known for its high-quality voice calls.
The voice clarity on my GSM phone during calls is consistently excellent.


CDMA does not typically use SIM cards for subscriber identification.
My CDMA phone was tied to one carrier, as it didn't have a SIM card.


An international telecommunications standard for the transmission of voice and data between cellphones and other mobile devices.

Common Curiosities

Which is more prevalent worldwide, GSM or CDMA?

GSM is more prevalent globally.

Can CDMA phones be used internationally as easily as GSM phones?

No, CDMA phones typically have more limitations on international use.

Is it easier to switch phones on a GSM network?

Yes, due to the use of SIM cards.

Do GSM phones offer better call quality than CDMA?

Both offer good call quality, but it depends more on the network conditions.

Is data speed faster on GSM or CDMA networks?

Data speeds depend more on the network technology (3G, 4G, LTE) rather than GSM or CDMA.

Which technology is newer, GSM or CDMA?

Both were developed around the same time, in the early 1990s.

Can a GSM phone work on a CDMA network?

Generally, no, unless the phone is specifically designed to be compatible with both.

Are CDMA phones more secure than GSM?

CDMA's unique encoding offers a level of security, but both have security measures.

Are CDMA phones tied to a specific carrier?

Originally yes, but newer CDMA phones offer more flexibility.

Do all GSM phones have SIM cards?

Yes, GSM phones use SIM cards for subscriber identification.

Are new smartphones using GSM or CDMA?

New smartphones often support both technologies, along with newer LTE standards.

Can I switch a GSM phone to a CDMA network if it has a SIM slot?

Only if the phone is designed to support both network technologies.

Can I use my CDMA phone in Europe?

It can be challenging as Europe predominantly uses GSM networks.

Will GSM and CDMA become obsolete?

With the rise of LTE and 5G, both GSM and CDMA are becoming less relevant.

Is it cheaper to use GSM or CDMA phones?

The cost depends on the carrier and plan, not the technology.

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Author Spotlight

Written by
Tayyaba Rehman
Tayyaba Rehman is a distinguished writer, currently serving as a primary contributor to As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.

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