The phones have there own basic common Technology. To know which one is the best and which devices and areas use at&t Gsm or Cdma you need to understand technologies in mobile phones. CDMA is short for (Code Division Multiple Access) and GSM is (Global System for Mobiles).

This all began with Sprint been the first to switch from analog to digital between the year 1996, CDMA having more potential than the GSM many decided to go for it and made it a number one preference. The Global System for Mobile Communications became adopted later in the entire globe for anyone who wanted to communicate using a cellular.

The Technology Behind At&t, CDMA or GSM

They both began and are still known for been the best multiple access technologies. CDMA and GSM change the face of mobile and multiple phone calls including the internet to make it one one radio channel. Most of the mobile devices sold on the market today come with a standard GSM version and a CDMA version, I personally have never come across one, that is compatible with both.

How It Works

They relay the signals through the simple transfer of a voice that gets transmitted and converted to a digital data. Data is assigned a channel, location and slot number with a ten digital code that would look like something similar to 111111111. Think of the code to be an identification number which represents text. If you are familiar with code this would be easy for you to actually understand. The computer reads a webpage written in code and serves the user a website, and yet in the background its takes HTML, Javascript and PHP to have a fully working website.

The pulsing of the time division signal created the notorious “GSM buzz,” a buzzing sound whenever you put a GSM phone near a speaker. That’s mostly gone now, because 3G GSM is not a time division technology. WCDMA is considered the 3G version of GSM technology. To further speed things up, the 3GPP (the GSM governing body) released extensions called HSPA, which have sped GSM networks up to as fast as 42Mbps, at least in theory.

CDMA networks, meanwhile, are stuck at 3.6Mbps. While faster CDMA technologies exist, US carriers chose not to install them and instead turned to 4G LTE to be more compatible with global standards. The global spread of GSM came about because in 1987, Europe mandated the technology by law, and because GSM comes from an industry consortium. For instance in the US, networks such as Sprint, Verizon, and US Cellular use CDMA. The other two AT&T and T-Mobile use GSM. The rest of the world uses GSM.

CDMA, is owned by chipmaker Qualcomm. This made it less expensive for third parties to build GSM equipment. GSM is most popular in the United States and Russia. However, it’s also used in some Asian and African countries, often alongside competing GSM carriers.

Can You Switch Between CDMA & GSM ?

The technology you use is much less important than the way your carrier has built its network. There are good and bad CDMA and GSM networks, but there are key differences between the technologies. Here’s what you, as a consumer, need to know.

It’s much easier to swap phones on GSM networks, because GSM carriers put customer information on a removable SIM card. Take the card out, put it in a different phone, and the new phone now has your number. Under GSM, a carrier must accept any GSM-compliant that comes with the phone. GSM carriers don’t have total control of the phone you’re using because the information is stored in the sim card.

All Sprint and Verizon phones now have SIM cards, but that isn’t because of CDMA. The SIM cards are there for Sprint’s and Verizon’s 4G LTE networks, because the LTE standard also uses SIM cards. CDMA carriers use network-based white lists to verify their subscribers. That means you can only switch phones with your carrier’s permission, and a carrier doesn’t have to accept any particular phone onto its network.

Which One Is Better CDMA or GSM?

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. In the United States, major carriers (Verizon and Sprint) use CDMA while the other two (AT&T and T-Mobile) use GSM.

Which One Is Better CDMA or GSM?
  • 3G CDMA, can’t make voice calls and transmit data at the same time. Once more, that’s an available option (known as SV-DO for Simultaneous Voice and Data Optimization), but one that US carriers haven’t adopted for their networks and phones.
  • Verizon 4G phones can do simultaneous voice and data because they route it all over LTE, avoiding CDMA entirely.
  • 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.
  • All 3G GSM networks have simultaneous voice and data, because it’s a required part of the spec. If you buy a CDMA phone from a third-party retailer, you’ll need to call your carrier to have it activated. If you buy a GSM phone, you’ll need to purchase a SIM card to put into your phone that will activate your phone’s network capabilities.
  • 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. Code division turned out to be a more powerful and flexible technology.

  • “3G GSM” is actually a CDMA technology, called WCDMA (wideband CDMA) or UMTS (Universal Mobile Telephone System). WCDMA requires wider channels than older CDMA systems, as the name implies, but it has more data capacity.
  • CDMA phones bake in compatibility restrictions that are difficult to get around, while GSM owners can simply take out their SIM and replace it with one from another carrier.
  • CDMA networks do not allow the use of a phone originally purchased from another carrier even if the phone is otherwise technically compatible. This is an important restriction to remember when going with a CDMA network.

What Should I Use In The US?

These 1990s-era technologies are typically cheap to buy and use, but they’re very inefficient users of the airwaves. Therefore in America it is actually recommended to use a system that sends more data. Carriers are switching their channels from inefficient older technologies to the more efficient 4G and 5G systems. Don’t buy a at&t Cdma Or Gsm 2G, 3G, 4G GSM phone in the US in 2019. US carriers are moving away from both CDMA and GSM, which will make some basic, flip, older, or foreign phones stop working in the US—if they haven’t stopped working already.

If you have a 2G voice phone, it will stop working soon, if it hasn’t already. Ideally, you should switch to a 4G phone as soon as possible for the best coverage and quality. AT&T has already turned off its 2G GSM. T-Mobile has reduced its 2G coverage so it’s only useful for machine-to-machine devices like fleet trackers and vending machines, not phones.

To conclude , neither GSM or CDMA is technically better; they ultimately provide the same service. These technologies in my view network quality depends on the carrier, not the cellular standard used. GSM phones can be unlocked and switch carriers, whereas CDMA phones are locked to a carrier. It’s usually cheaper to buy unlocked GSM phones with at&t than CDMA phones.

LTE is being rolled out as a global standard. Unfortunately, it falls victim to even more frequency division than GSM and CDMA. The technology also suffers from limited adoption because it’s relatively new.

You need to check what bands your chosen phone supports carefully. Most either work on GSM or CDMA, and both standards offer multiple frequencies that differ across the globe.