What should I pick? GSM vs CDMA
Updated post: Since 2021, Tello Mobile has switched to GSM, and it’s now a GSM-only network.
Tello does not support CDMA any longer.
To be or not to be? CDMA or GSM? This seems the only logical question you can ask yourself when you stand before the laptop screen and don’t know what kind of phone to pick.
But since a smart user is an informed one, before you make your choice, you need to know the difference between the CDMA and the GSM technology. Here is some useful info that will surely bring some light on the matter!
What are the main differences between CDMA and GSM?
CDMA stands for Code Division Multiple Access, while GSM stands for Global System for Mobiles. Both are major radio systems used in cell phones and gather a bunch of technologies too complicated to understand for a non-technical user without a PhD in Telecommunications. Long story short, major mobile carriers run on one of these two technologies. And in order to pick your phone you need to know what carrier uses what technology.
But how can you tell which phone is running on what technology?
Well, here are a few pointers!
- GSM mobile carriers provide their handsets with a removable SIM card that stores customer information. If you have a GSM phone and want to get a new phone, simply remove the SIM card and your new phone will have your mobile number together with other data you saved on the SIM card (contacts, PUK number, etc).
- Well, CDMA phones don’t work the same way! CDMA phones don’t store network data on a SIM card, but verify that data against a network list. So, if you have a CDMA phone and want to switch providers, you will need to ask for your carrier’s permission. Plus, most CDMA phones don’t have SIM cards. If they do, their role is not the same as for a GSM ones. If you see a CDMA phone with a SIM card slot, it means that the phone needs a card to use the 4G LTE technology. But that’s another story!
Watch this useful video that presents the differences between CDMA and GSM technologies even better:
So the true question is not what to pick between CDMA or GSM! But: what type of technology does this mobile carrier use?
Because, if you already know what mobile carrier you want to join, you need to figure out what type of phone to get: CDMA or GSM!
Which mobile carriers are CDMA and which are GSM?
This is an easy one!
AT&T and T-Mobile use GSM. Sprint, Verizon and U.S. Cellular use CDMA. Since Tello runs on a nationwide 4G LTE network, you need to check your phone’s compatibility on our site to see if it’s a match.
What phone can I enroll into Tello?
So, since the CDMA vs GSM dilemma is now unravelled, you might also wonder what phones are able to join our Tello network. Simple! They have to meet any of the following criteria:
- New devices that support voice over 4G (VoLTE)
- minimum requirements LTE frequency bands 2, 4, 12 + VoLTE and when talking about an ideal connection: bands 2, 4, 12, 66, 71 + VoLTE.
And if you’re still not sure, you only need your IMEI (also known as ESN/MEID code) to check for yourself on our Bring Your Own Phone page. The process is simple and does all the work for you.
Once you enter your IMEI, you will follow several steps:
- Find out if your phone can join Tello or not
- Get a New SIM (you can buy one online from Tello.com)
- Decide whether you want to port in your old number or get a new one from Tello
How do you judge how much data you need in your plan?
Martha 357
I just looked at my last few bills to see how much data I usually use. I found out I use a lot less than I thought, so it is worth logging in and checking your past data usage.
Cindy,
I would start with 1GB and see how it goes. If you don’t use data-hungry apps (video streaming, Google maps, etc.) over 4G much you shouldn’t have an issue. I use pretty basic apps and mainly use my phone for e-mail, talk, & text. 1GB have worked great for me for the last year.
Hi Cindy!
The best way to do this is to estimate and add the amount you think you need.
If you realize you need more or less you can always upgrade/downgrade your plan. The change will be instant (once the payment is processed) and if you have any unused balance when you upgrade/downgrade your plan that unused balance will roll over for the next 30 days.
Hope this helps!
Michelle,
On behalf of Tello.com
I have a Windows 8 phone with VERIZON. It is incompatible with Tello, so the information contained within the video is NOT all correct. Obviously, Verizon uses GSM, NOT CDMA.
BAD video!
Hello,
The video is not our property, but it’s very useful for many users to understand the main differences between GSM and CDMA.
Of course, just like you said it “is NOT all correct”. That’s why the safest way to check if a phone is compatible with Tello is to enter the ESN/IMEI on our Bring Your Own Phone page. They system will tell you right away if you can bring it into Tello or not.
Thanks a lot for you comment!
Michelle,
On behalf of Tello.com
Verizon uses cdma sir…….
Verizon is dropping its CDMA because it is only tech that is not used by many outside the US. GSM is the newer and better tech. Verizon does SIM card unlocked CDMA cell phones now and is dropping CDMA in 2019. yes I hate CDMA for many many reasons. I don’t like when companies try to control what we can do and can’t do. Most of the rest of the world doesn’t put up with it lol.
Thank you for correcting the error of the quick-draw, indignant poster with such patience and politeness..
I put in my ImeI number and I need a sim card, but mine wont work with Tello either.
Seems mine won’t work with GSM either. I got it from Wish.com, don’t know what to do!
No matter what imei you put it will say that its not supported. They want you to buy their phone. This defeats the purpose of having a dual sim phone.
Joy,
Sorry to hear about the issue. Could you please bring this matter up with our Customer Support team and see what they can do about it? Thanks & fingers crossed!
It says mine is comparable.
dude, Verizon uses CDMA. The fact that your phone is locked to Verizon for their own marketing strategies in no way authorizes you to spread misinformation .. Do some research rather than flaunt your ignorance.
I have a 5S cell I bought at Verizon. I never used it and cancelled the plan about 5 years ago.
I entered the IMEI and it says I can only use it to replace a CDMA cell already on Tello.
I do not have any Tello lines.
How can I use it to set up a new line?
It does not have a SIM.
Thank you.
Hi Christine,
No worries, I can give you more details.
The phone you have is definitely a CDMA one, so you can not bring it to Tello. We currently run on GSM (we’ve recently switched from CDMA to GSM), therefore all new Tello lines need to have a GSM compatible phone.
Unfortunately, you’re receiving this message as an exception – if you were an old customer, you would be able to switch your current CDMA phone with this one. Still, since you are new you’ll need to purchase a GSM device and bring it along.
Hope I answered your questions, please let us know if there is anything else you need to know and, thank you so much for your interest in our company.
As I understand, Verizon is going with VoLTE and will later drop CDMA.
Hello, my grandfather has a tmobile flip phone will this work on your network? thank you
Dear Ashley,
If the flip phone is a CDMA device and is unlocked, you need to enter the ESN on our Bring Your Own Phone page to check if you can enroll it into Tello.
My colleagues from Customer Service can also help you with this, but you will have to provide them the ESN/IMEI number.
Thanks for contacting us!
Michelle, on behalf of Tello.com
You can also watch video’s on utube how to unlock your phone!
Thank you for this article! This seems very clear and straight-forward. Just what I was wondering (and yes, I did join Tello today)!
We’re glad you like it Rachael!
I want to know more about the Tello app, whether it is going to add cost to anything I do on the “pay as you go plan”, and if not, I need instructions for how to download and install it on my CDMA Sprint LG Rumor 2 phone. I’ve never used data on a cell phone before, always had dumb prepaid flip phones that I just used for calls and texting. So I am really going to need a step by step how to instruction set, which is how I ended up on your tutorial page.
My preference was to access my account activity via my computer on your webpage, in hopes of downloading the data as a .csv file that I can work with in Excel, but so far as I could see, that wasn’t an option as it was with Ringplus. I did print the data to .pdf, but that doesn’t let me sort entries or sum numbers the way a .csv file would. I also found it unsatisfactory that only the destination number was displayed, not the originating number, which means I can’t know which person kept me on the phone for how long. Does the Tello app support downloading activity data, and if so, what file format, and is there any way to sent the file from my phone to a computer so I can get it into a spreadsheet and work with it? Or is there a way to download activity data via your website direct to my computer?
Hello,
Unfortunately, the app can’t be installed on an LG Rumor 2, because it is only available for Android and iOS devices.
In any case, using the Tello app will not cost anything besides the credit you spend with your calls. It does require however an Internet connection (either WiFi or data). The app shows your calling activity, but the information is not downloadable.
Your Tello team
Will Tello ever consider offering GSM service?
Hello,
Since Tello runs on Sprint’s network and Sprint only offers CDMA service, unfortunately we won’t be able to offer GSM service.
Thank you!
Well Now Tello Just published a blog about moving services to GSM from CDMA very soon after 2021 CDMA will be a thing of the past and LTE will be a main standard as we move towards to 5G. To Simply understand 5G. refer to t-Mobile.com/5G
I have an old Samsung Prepaid phone by Verizon (probably from 2009) Model: SCH-U350 and when I dial the *#06# I am connected to Verizon where I can buy minutes, get a new phone number, etc. This phone is old so currently does not have a phone number. I do not see a SIM card/slot on the phone and it’s a Verizon phone so I assume it’s CDMA. Can I still use Tello? THANK YOU!
Hello,
If it’s a Verizon phone, then it’s locked in the Verizon network and cannot be used with any other network, including Tello.
Thank you!
What’s different between CDMA v.s MVNO. Which one is best signal? I guess MVNO is VoIP?
Hello,
An MVNO is a wireless provider that uses the network of a major operator to offer its own services. For instance, Tello is an MVNO that uses the Sprint network. VoIP providers offer their telecom services over the Internet.
Did you mean the difference between CDMA and GSM? These are the two basic technologies in mobile telephony. Both can offer high quality or poor quality service, depending on the brand you choose. You can check the signal/coverage for each network on its own website. Just remember that if you want to use a phone you already have, it is only compatible either with CDMA or with GSM technology. Here is more information on this subject: http://www.pcmag.com/article2/0,2817,2407896,00.asp.
Your Tello team
I have a Samsung S4, which is (per my internet research) compatible with bandwidths for BOTH CDMA and GSM. I bought it from a company (probably) affiliated with TextNow.com CDMA service, where I am currently using it. It apparently passed the compatibility (simple) test to work with MintSim.com’s GSM service. Tello seems to be HIGHLY competitive, pricewise, with MintSim, ESPECIALLY if I did not want data (i.e., Internet).
I have Spring sim CDMA part number is SIMGLW436C. This sim haven’t been activated. Can I use it with Tello. I have a iPhone 6 model A1549 unlock
I’m on H2O pay as you go right now. Thank you for response my question
Hello,
In order to check if your phone and SIM card are compatible with Tello, we kindly ask you to provide us the IMEI of the iPhone 6 and the ICCID of the SIM card you have. Please contact our customer service team as soon as you have the information or try to enter the codes here https://tello.com/bring_your_own_phone.
Thank you!
Hi – About BYO iPhone SE for Verizon A1662 (unlocked by Verizon, not Apple factory unlocked) versus the iPhone SE for Sprint A1723, are the same limitations applied to Tello regarding 4G data speeds being limited by the different LTE channels?
Hi! No worries in this respect, as both devices benefit from the same 4G speed.
hi, do unlock phones other than iphones and nexus work on Tello?
Hello,
Any unlocked phone should work with Tello, regardless of its brand. In order to make sure that a phone is compatible, please check its IMEI number on the Bring Your Own Phone page: https://tello.com/bring_your_own_phone. Or you could send the phone’s ESN number to our customer service team and they will check for you.
Thank you!
The above statement seems to say – The only people that can use Tello are
unlocked CDMA iphones 5S to SE (so 6 and 7 are out) devices free of contract, developed for Sprint or for other Sprint MVNOs AND are and Nexus 5-6P.
Is this right? What if you have a HTC One M8 (unlocked) Windows Phone? That’s an unlocked Sprint CDMA phone. Will that work? If not, well there’s a 2 word review for Tello that equivalent to the two word review for Spinal Tap.
Hello Gene,
Your phone should work just fine on Tello, but in order to make sure, please go the Bring Your Own Device section and check the IMEI.
Fingers crossed!
its too bad tello doesnt have gsm. i have a phone i bought overseas that i would like to use
I have a OnePlus phone whose IMEI isn’t recognized when I enter it in your lookup system (same with AT&T, although it works with AT&T). It’s specs say it has WCDMA 1/2/4/5/8. Would it work with Tello?
Hey Patrick,
Please contact our customer service and provide ESN code so we can identify why his device is not accepted.
Fingers crossed,
Maria
I have a BLU studio xl 2 will it work on tello 354559081641786
Hello,
Please check your phone here: https://tello.com/bring_your_own_phone. Fingers crossed!
Have a great one!
My phone is compatible with your system but the Sim card is not?
Hi, thanks for writing!
You can always get a new SIM from us. If you have questions about the type of SIm needed, please contact our Support Team and they’ll be happy to assist you!
Have a great one!
What do i need if i want to use the phone in south africa and in america do i need GSM or CDMA!!!?
Hi Jacob,
Unfortunately, that question is not related to GSM vs CDMA. You need roaming to use the same phone when abroad. Please do some more research on this, thanks & safe travels!
Unfortunately, my question is not related to GSM or CDMA, but I cannot believe how many people are still using such old outdated phones. It costs more to fill up your tank than to buy a cheap, basic phone these days. Why are so many people trying to keep alive their first antiquated phone they purchased 10 years ago?
I know it’s more to do with ignorance.
How long did it take for you to upgrade from rotary to touch tone?
If your phone is more than 3 years old, it’s time to spend $25 for a new one.
You can actually use any iPhone as long as it’s cdma compatible and works with sprint
I’m currently using Samsung J7 and it does have a SIM card. Can I use tello without switching to a new phone?
Hi there,
In order to know for sure, you still need to check it’s compatibility here: https://tello.com/bring_your_own_phone. You can get a SIm from us, no worries! Thanks :)
will an iphone xr (unlocked from Sprint CDMA n/w) work ? I see a comment that says iphone from 5 to SE only work on tello.. pls confirm..
Hello there, sorry for the delay.
The only way to make sure is to check it here: https://tello.com/bring_your_own_phone, thanks a bunch!
I want to switch over to Tello. I currently use Tracfone which is both GSM and CDMA. My phone does use a SIM card. Would it work on Tello?
Hello there, the only way to make sure is to check it here: https://tello.com/bring_your_own_phone. Thanks for reaching out & fingers crossed!
Will the Tello service be affected by the possible T-Mobile buy-out of Sprint?
Hey, Matt,
Thanks for the question. We have no news about this yet, but our customers will always be the firsts to know if anything should change. Off the record, we’re only expecting good things to come to Tello :).
When I purchase a “used” ($30) Jitterbug phone – will it work with Tello?
Hey there, any phone needs to be Sprint Ready, CDMA in order to join Tello, but to make sure, you can check its compatibility here: https://tello.com/bring_your_own_phone. Thanks!
Will Samsung Galaxy J3 Luna Pro (S327VL) work? It is a tracfone phone and it says CDMA.
Evelyn, thanks for the question! to make sure, please Dial *#06# and you’ll receive your phone’s ESN/IMEI/MEID code & enter it in our compatibility checker: https://tello.com/bring_your_own_phone. Fingers crossed!
Is it also true that CDMA phones do not have the ability to talk on the phone and use the internet at the same time? Sprint has this “problem.”
Hi, Sean,
Now, this is interesting. As far as I know, this used to be an older issue, currently solved. Also, it was only related to iPhones, due to a hardware issue.
What about unlocked Verizon Blackberry phones, or does unlocking just unlock the GSM portion?
Hey, Matt,
Unfortunately, Blackberry phones are on the list of non-compatible devices with Tello, sorry. If, however, you have another phone brand, please check its compatibility here: https://tello.com/bring_your_own_phone. Thanks!
Can I use iPhone 8 and 8+ from Sprint
Hi, Eugene,
I think they’re a match, but just to be sure, you’d have to check them here, by entering the ESN: https://tello.com/bring_your_own_phone, when you’re going through the bring your own device process. Thanks :).
OK
Can i transfer my metro pcs phone number to tello?
Or where can i buy a tello phone to put my phone number?
Hello,
You can keep your device and your phone number when porting to Tello. Please check your phone’s compatibility here: https://tello.com/bring_your_own_phone. If you’re thinking about getting a new phone, make sure it’s CDMA, Sprint compatible & unlocked. You can always see our selection of devices: https://tello.com/phones.
Here is some needed info when switching from another provider to Tello: https://blog.tello.com/news/how-to-port-your-number-to-tello/.
Hope this helps, thanks!
Hey tello i like your price . My main question how hard is porting in and out a number? how customer severice like ? Can i pay bill over phone ? lastly where to find a unlocked cdma flip phone and sim card?
Hi, Leo,
Thanks for the message :).
Porting your number is very easy, you can even do it yourself.
If you want to port your number to Tello you first need to see into which category you fall:
1. if you bring your own phone and you don’t need a CDMA SIM, simply fill in the port-in form provided while going through the bring your own phone process.
–if your number is Sprint® Network* active, the port in is mandatory
–if your number is not active on Sprint® Network*, you have the option to port in your old number or get a new number from Tello during the bring your own phone process
2. if you purchased a phone or a CDMA SIM from us, then after you receive the package and activate the phone, you need to go to the Port-in section of the My Phone page and follow the steps;
3. if you already have an active line with Tello and want to port in a new number to replace the existing number, just go to the Port-in section of the My Phone page and follow the steps;
In order to port a phone number into Tello, you will also need some details from your current provider. You will need:
–Phone number you want to transfer
–Account number
–Port-out PIN/Password
–First name and last name as listed on the phone bill
–Your address as listed on the phone bill
Some carriers do not have port-out pins/passwords.
Consult our Carrier Transfer Information to help guide you in the right direction — https://blog.tello.com/news/how-to-port-your-number-to-tello/.
As for the phone, we currently have this one: https://tello.com/buy/phones/coolpad-snap-refurbished-black-512mb – that meets your requirements. You can get a SIM from us, of course.
Hope this helps, thanks!
I have a question about accessing my account.
I ported my number into Tello, bought a new Samsung A6 phone, it was delivered yesterday, and my number was completely ported this morning, after an email that it was good to go.
Now I can’t access my account on my PC/notebook, or my phone either.
I can access any other webpage, as I am here, but if I go from here to try to access my account, since this is a Tello page, I get a screen that says the website was too slow to answer, it wouldn’t connect.
How can I fix this problem? I didn’t have this problem yesterday, before the number was ported to this new phone, but now, since it was finalized, I can’t access my tello page on my pc or my phone.
What gives? This is really a bit aggravating to say the least.
Thanks to anyone who can help me with this problem.
I have contacted Customer service at Tello.com to see how to remedy this problem.
I hope it’s solved by now, Sharon. Good call on contacting my colleagues from Customer Support, they’re always full of answers. Thanks!
OK since Tmobile has bought out Sprint. Is the CDMA phones going to work?
I mean Tmobile is GSM.
Lisa, great question, I think a lot of people are wondering just how the Sprint – T-mobile merger will work for Tello customers. For now, things remain as they are, but as soon as we have news on this, we’ll compile everything there is to know and prepare the needed info for all our customers. Stay Safe, thanks!
Will a Doro 7050 unlocked GSM phone be compitable to your operating system?
Tom, please get your device checked here: https://tello.com/bring_your_own_phone, thanks!
OK. I have a CDMA cell phone with Tello now. If I buy a GSM phone can I still keep my same phone number if I switch to a GSM phone? Or am I locked in to the CDMA network?
Hi, Jeff, you can bring a GSM phone to Tello and keep the same number, no need to worry. Thanks!
Many people would like to buy cell phones elsewhere, especially since you don’t have much of a selection when it comes to flip phones. Why can’t you give more information on phone models which are compatible? It becomes extremely difficult to check around for a phone if we always need to get the imei number
Its says my phone is GSM compatible but not CDMA can I still use it my old phone is giving out would like to use this phone
Hi Carlos, definitely YES!
If you already checked your phone on our Bring Your Own phone page and it says it is compatible, you can surely use it on our network.
Please continue the process, order a Tello GSM SIM and once you receive the SIM you’ll need to activate it.
We’ll be waiting for you!
I wonder if the Samsung Galaxy J2 will work wit a Tello SIM card? Considering buying both, but want to make sure there aren’t compatibility issues.
Hi FolkFaith,
You can easily check this on our Bring Your Own Phone page by entering the IMEI of the device. If you get the message that the device is compatible with our network, then you won’t have any issue joining Tello.
Your company quoted the following:
“AT&T and T-Mobile use GSM. Sprint, Verizon and U.S. Cellular use CDMA. Since Tello runs on a nationwide 4G LTE network, you need to check your phone’s compatibility on our site to see if it’s a match.”
Thus, your comments still leaves a question ” do you buy a CDMA or a GSM or does it not matter since its a LTE ?
thank you for your time
sincerely, shirley evers
Shirley, thanks for writing.
We work on GSM, so you’ll need a GSM SIM from us and a GSM & VoLTE compatible phone in order to join Tello.
Hope this answers your question,
Maria
Your company quoted the following:………. .”
……..do you buy a CDMA or a GSM or does it not matter since its a LTE ?
Sorry i didnt know it took the comment the FIRST TIME…
your side arrow is very light and i thought it was the arrow to make the comments to scroll down..however it didnt it took me to a new page and when i came back my message to u disappeared..
thank you for your time
sincerely, shirley evers
What tablet that has a sim card slot will work with Tello?
Please be advised that the Tello SIM card is universal. It will fit in any tablet/ device. It’s a 3 in 1 SIM Kit.