What’s The Difference Between CDMA and GSM Phones?
Here’s What You Should Know
Whether you travel abroad a little or a lot, staying connected to work and family is important. But this may be more complicated if the communication technologies are not compatible. In this article, I’ll address the difference between CDMA and GSM phones and give you options on how to stay connected without spending a fortune.
The first question you may be asking yourself is, what the heck is CDMA and GSM? More importantly, why do you need to know? Let’s start with CDMA.
I travel between Ireland and the United States at least once a year. Over here in Ireland, we have GSM phones. Each year, I’m looking for new ways to stay in touch on both sides of the pond that won’t break the bank. But CDMA technology has made that more difficult.
What is CDMA?
CDMA stands for Code-Division Multiple Access. This is a protocol for transmitting information found in older 2G and 3G wireless communications. This allows for the conversion of analog to digital by converting audio into binary elements.
Remember back in the mid-1990’s when mobile phones first became a thing? Everyone was so excited about flip phones. I know I was. I hung onto my Motorola flip phone for as long as possible.
At that time, CDMA was the fastest technology and the most popular. The technology was built into the hardware of mobile phones, making them cheaper to manufacture. The downside was that your mobile phone was locked in with a particular network carrier like Verizon, Sprint, or AT&T. So if you travel internationally, this is a problem. With GSM technology, this isn’t a problem.
What is GSM?
GSM stands for Global System for Mobile communication. GSM is a digital technology used in mobile communication. It uses four different frequency bands–850 MHz, 900 MHz, 1800 MHz, and 1900 MHz. This allows for both voice and data communication on your mobile phone. GSM is used in many European countries.
How Did We End Up With Two Different Technologies?
Verizon, Sprint, and U.S. Cellular use CDMA. The two technologies are not compatible–you cannot swap between the two. How did this happen? The chipmaker, Qualcomm, owns CDMA so the radio frequency is built into the hardware of the cell phone. The two biggest players in mobile phone service, Verizon and Sprint, had to make a choice between CDMA and GSM. Because CDMA was the fastest and cheapest, they chose CDMA.
Also, at that time, CDMA offered better call quality than GSM. In the meantime, GSM not only caught up but surpassed CDMA. Here are a few differences you should know:
- GSM is both voice and data technology whereas CDMA is only voice.
- Sim cards are needed for data technology. Even the newer 3G CDMA can’t transmit data and make calls at the same time.
- At the time, CDMA towers could accommodate more subscribers than GSM towers making it a cheaper route as well.
GSM Radio Frequency
So here’s the difference. While CDMA phones have all their carrier information built into the phone, GSM phones (used by AT&T and T-Mobile) carry all their carrier information on a sim card making them beautifully portable, right? Maybe.
GSM phones are more widely used in European countries while CDMA phones are more widely used in the USA. With CDMA phones, you can’t switch phones without your carrier’s permission. Even if you wanted to switch carriers, your carrier may prevent it (check Terms and Conditions).
Can These Technologies Coexist?
Sprint and Verizon have had to make the leap into sim card phones in order to provide data service on their 4G LTE networks which are sim card based. And CDMA carriers may not allow you to bring your own CDMA phone to their network. They could, but they typically don’t. At the time of this writing, Sprint rejects any non-Sprint phones.
So if it’s this difficult within the United States, how can you expect to stay connected outside the U.S.? That’s where unlocked phones come in.
What If You Already Have An Unlocked Phone?
If you are travelling abroad and have an unlocked CDMA phone, having it unlocked won’t necessarily solve your problem. You can’t simply buy a sim card, put it into your phone, and start talking, texting, and sending pictures. CDMA phones don’t have sim card slots.
If you have a GSM phone and your carrier is AT&T or T-Mobile, you could get the phone unlocked and purchase a sim card before you travel to the country you are visiting. It would be wise to consult your carrier on whether your unlocked phone will work abroad.
There are exceptions. For instance, Verizon’s iPhone 6 was both CDMA and GSM compatible.
Considerations
Now that you have all this information, what does it mean for you? Here are a few things to think about before you travel:
How new is your phone?
If it’s an older phone, the technology may not be compatible with where you are travelling to.
Is your phone unlocked? Can it be?
This is a question for your carrier. But keep in mind that if you still have a CDMA phone, getting it unlocked may not help you.
Do you have an iPhone?
If you do, it’s possible that it is not only unlocked but it is compatible with both CDMA and GSM technology. Even an older iPhone may still work in this case.
How to Tell If Your Phone is CDMA or GSM or Both
If you have an iPhone, here’s how to find out:
- Go to Settings
- Scroll down to General
- Then scroll to About
- Note the Model number. Then do a search on the make and model of the phone with the term ‘GSM or CDMA’ included.
For instance, I have an older iPhone 8 that was purchased in the United States and has a slot for a sim card. It has two model numbers: A1863 and MQ6L2LL. This means that my phone is both CDMA and GSM compatible.
Good News/Bad News
The good news is that many U.S. carriers that still use CDMA technology are also implementing GSM technology as well. In the case of Verizon, their phones now use both technologies.
But here’s the bad news. Your Verizon CDMA phone will work in Europe but that doesn’t mean you can swap out a sim card while you travel. In fact, the way it works with Verizon is that you have to turn on Data Roaming and pay a daily fee for using your phone outside the U.S.
- Verizon TravelPass: For Canada and Mexico this is $5/day
- International Monthly Plan: For trips that are 10 days or more–$100.
This allows you to roam while travelling and can become very expensive. For specific details about travelling with your phone, check with your carrier.
I know what you’re thinking, “why can’t I just use wifi and use the phone via Whatsapp or Facebook?” That’s also another option but it’s messy. In fact, I’ve tried that, too. It didn’t work well at all. Why? Trying to find free wifi was a hassle. Not to mention the call quality wasn’t great.
One Wrong Turn
Last year when I went to the U.S., I decided not to buy a prepaid sim card. I thought I’d just get by with free wifi since I’d be spending most of my time visiting individual homes where everyone has Internet.
That’s where it becomes a problem. In my case, I was given directions to a friend’s new home. I downloaded the map so I wouldn’t need data. Everything was going fine until I took a wrong turn. That’s when the map couldn’t recalculate. I was driving around trying to find a place where I could contact her. And of course, I couldn’t call her.
T-Mobile to the Rescue!
Luckily, I found a mall. I went inside, connected to their wifi and called my friend via Facebook. While I waited for her, I spotted a T-Mobile store. I bought a sim card and plan for two weeks. Problem solved.
So now that we know all this, what are the options? First, you need to ask yourself a few questions.
How do I know if an unlocked phone will work with my carrier?
All unlocked phones work on carriers that use GSM networks. There are many GSM networks in the U.S. including AT&T, T-Mobile, Cricket, MetroPCS, Tracfone, and Simple Mobile.
Are Tracfones CDMA Or GSM?
The answer is they can be both. This will depend on the model of the phone. For instance, if the model number ends with a ‘C,’ it’s a CDMA phone. If the model number ends with a ‘G,’ it’s a GSM phone.
Is CDMA Or GSM Better?
Many carriers are now switching over to GSM simply because GSM is a better, more advanced technology. CDMA technology is being phased out.
Do CDMA phones still work?
Yes. CDMA phones can work on GSM networks as long as it’s a 3G network. But this is a moot point now because 3G will be discontinued by the end of 2022.
Can a CDMA Phone Be Converted to GSM?
This is not possible. They are two different technologies and they are not compatible with each other. Remember that the CDMA transmission protocol is built into the hardware of the phone. While GSM is portable because it resides on a sim card.
So What Are Your Options?
- Get Your Phone Unlocked: This will work if your phone is a GSM phone. This option allows you to buy a sim card or an esim in the country you are travelling to.
- Get a Second Hand iPhone: This is one of the best ideas because these phones are GSM/CDMA and automatically unlocked to any network. Likewise, you can buy a sim card or esim for this option.
- Buy a CDMA or GSM phone: it’s best to do this when you get to your location. Then you know it will work.
- Buy a Data Roaming Plan: Be sure to check the details on how many minutes and how much data upload/download is included.
Personally, I think Options 1 and 2 are the least expensive options if they are possible for you. Option 3 may be worthwhile if it’s a short trip and you don’t travel outside the U.S. frequently.
I have an old iPhone 8 so each time I go to the U.S., I just head over to T-Mobile and get a sim card activated for my visit. Then when I land back in Ireland, I put my local sim card back in my phone. Easy peasy.
But before I had an iPhone, I kept an old phone that had a sim card slot. I bought a Tracfone at Walmart once but it was quite expensive. Between the phone and getting it activated, it set me back around $80. And my trip was only for two weeks! A sim card at T-Mobile including activation was only $30.
Final Thoughts
Here’s the good news. With the advancement of wireless technology, CDMA is becoming obsolete so you probably won’t need to worry about this much longer. Many U.S. companies are switching their customers over to GSM.
Having a GSM mobile phone gives you a lot more flexibility. Not only can you swap out the sim card when you travel, but you can also abandon contracts altogether by using prepaid plans that you can add money to whenever necessary.
If you have to upgrade your phone, it’s a good idea to keep your old phone just in case. You never know when you might need it when you travel.
I hope this information has been helpful for you in explaining the technology and deciding whether you need to buy another phone for travel or not. Feel free to let me know your thoughts!
