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GSM and CDMA phone bands....

My friend bought a new phone, last week .She was so happy with deal .But after the phone is delivered ,she understand that her phone works in CDMA. she asked me what to do?? ?Because she wants to switch to her old carrier .what do you guys suggest?? If the phone specification is marked as CDMA, will it work in GSM??

I want to write a blog for all my readers explaining the difference between CDMA, and GSM. So next time you guys will understand the difference between GSM and CDMA .

What is the difference between CDMA and GSM phone bands?

GSM and CDMA are frequency bands that support cellular service. they can have a significant effect on phone carrier choice and can also affect phone type.

CDMA stands for “Code Division Multiple Access.” GSM stands for “Global System for Mobiles.” They are two radio networks used by wireless carriers. If the phone is designed to work in any one of the band .Then it won’t work in another band. phones were designed to operate on any one type of network , are incompatible with the other. Depending on the specific phone and the carrier, you might have found that you were ineligible to transfer a device you owned to a new carrier’s network.

Some newer devices are considered dual-band phones and can run on both technologies. If you’re looking to hop from one carrier to another you need to look through product specifications to see if it’s compatible

GSM transforms calls into digital data, gives them a shared channel and a time slot, and puts the pieces of each call back together for the listener on the other end. GSM came first. It's a "time division" system. Calls take turns. Your voice is transformed into digital data, which is given a channel and a time slot, On the other end, the receiver listens only to the assigned time slot and pieces the call back together

CDMA encodes each call’s data with a unique key. Then all calls are transmitted at once, with receivers “dividing” the combined signal back into individual calls. CDMA requires a bit more processing power. It's a "code division" system. Every call's data is encoded with a unique key, then the calls are all transmitted at once; if you have calls 1, 2, and 3 in a channel, the channel would just say 66666666. The receivers each have the unique key to "divide" the combined signal into its individual calls.

GSM is more widely used around the globe, with availability in more than 200 countries. While CDMA is used widely in the U.S., it is less common elsewhere .In US AT&T and T-Mobile are GSM wireless networks, Verizon uses CDMA technology and is the largest wireless carrier in the US.

Between GSM and CDMA, one isn't particularly better than the other, and both ultimately provide the same services — the quality of service depends entirely on the carrier and not on whether GSM or CDMA was used.

A noticeable difference is that with a GSM phone, it can be unlocked so users can switch between carriers easily. With a CDMA phone, it'll be locked to a carrier and won't use a sim card. Instead of an actual sim card a CDMA phone will be linked to the network via a phone number. Many CDMA carriers don’t allow you to do voice and data at the same time. However, CDMA networks tend to have better network coverage in rural areas. the most crucial distinction between the two is GSM allows you to make calls and use data at the same time while CDMA doesn't.

In the old days, one of the easiest ways to tell the type of band supported by a phone was whether it had a sim card slot or not. GSM phones had a sim card slot while CDMA phones didn't. CDMA phones don't need a sim card since the phone number is linked to the device itself.

However, with the advent of 4G and 5G networks, many smartphones have sim cards, so it's no longer an efficient method. But if your device doesn't have a SIM card slot, it uses CDMA.

Devices bought directly from manufacturers commonly support both CDMA and GSM for better compatibility.

However, carrier-locked devices are usually associated with a particular network band.Different carriers support different bands. Every wireless carrier sells devices that are compatible with its network band.

Smartphones from AT&T and T-Mobile are GSM-compatible since both carriers use GSM technology like most of the rest of the world. However, while Verizon is a CDMA carrier, it sells smartphones that support both GSM and CDMA. That means a Verizon unlocked smartphone can work on T-Mobile's or AT&T's GSM networks without issue.


Everyone's scrolling, Snapping, texting, FaceTiming, and more. Demands for mobile data use continue to rise. 2G and 3G, CDMA and GSM, are inefficient uses of the airwaves. 4G and 5G compress more information into each hertz of airwaves, and can combine channels much more flexibly for more efficient operation. So the carriers are retiring the older, less efficient technologies in exchange for newer networks which make better use of a scarce resource.

we are entering into 5G , the two network bands will continue to be less critical. For instance, major US carriers will start closing their 3G networks in early 2022.

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Jul 28, 2023
Rated 5 out of 5 stars.

thanks for the explanation even I, as a low tech person can kind a understand.

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