GSM vs CDMA – what is the difference and why should I care?
GSM and CDMA are two types of cellphone networks in the US. For the most part, if you have a phone on one network you can’t use it on the other. GSM means Global System for Mobile communications, which is a network that supports both cellular and data. The same goes for CDMA, which means Code Division Multiple Access
US Mobile currently only operates as a GSM network. What does that mean? Well GSM networks like US Mobile, T-Mobile, and AT&T use removable SIM cards. This means that unlocked phones from other American GSM carriers will work on US Mobile’s network.
On the other hand, Verizon and Sprint are CDMA carriers. CDMA carriers don’t use SIM cards and most CDMA phones are locked into their network. So you can’t use a Sprint phone on Verizon’s network or vice versa. Also, 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.
Advantages of GSM vs CDMA
- Easier to switch phones
- Easier to switch carriers
- If you travel abroad you can switch your SIM card for a local SIM (just don’t forget to Snooze your US Mobile plan first)
LTE requires a SIM Card
LTE, is a 4G wireless technology, developed to achieve high-speed data. All LTE networks in the US are using GSM technology, as CDMA Technology can’t handle LTE. Due to this, newer Verizon and Sprint phones all use a SIM card. Seeing as all new phones aren’t using CDMA, the question is if CDMA is on its way out completely?
If you’re planning on bringing your GSM phone to US Mobile you can find more information in Is My Phone Unlocked. Can I Bring It To Any Network?. Or if you’re looking for a new phone, check out our webshop for unlocked phones.
Although this may be true for US Mobile this information is outdated for cdma networks. Verizon, which is cdma has removable sim cards and now accepts unlocked phones on the cdma network, specifically Nokia 7.1. Straight talk has both cdma and gsm phones. And you can byop that is unlocked to Straight Talk. Finally, the Google Pixel series can be purchased unlocked from the factory (unless they were previous purchased through a network like AT&T or Verizon) and will work on both cdma and gsm networks.
The reason Verizon has a removable SIM is to take advantage of 4G/LTE (which is a GSM standard but almost entirely IP related), but it is still matching all it’s subscriber info against a ‘network white-list’ (which is what CDMA is doing compared to a SIM card that stores subscriber data). You can bring some CDMA phones over to a GSM network, but the device must be able to operate on many more frequency bands (like 600-900 MHz and 1800-1900 MHz including the LTE bands the provider uses (which can vary)) but as anyone who works in telecommunications can attest – this is really ‘best effort’ most of the time since at the core it’s still a CDMA device – and they are competing and incompatible technologies.
What does it mean when a seller says the phone is Gsm/Cdma? Is it that it works well as both or is it the same as an unlocked phone?
So when 3G was developed 2 different variations emerged – GSM & CDMA. Some carriers used CDMA and if you wanted to access their network you needed a CDMA phone. For GSM carrier you needed a GSM phone. If a phone is both then it will work with both. However, 3G is scheduled to be sunsetted soon, and most carriers will not allow activation on those devices (including us), unless the phone also has LTE ( the only one standard for 4G).
You could read mote about the differences of GSM/LTE/CDMA here: https://www.usmobile.com/blog/lte-gsm-vs-cdma/