If you’re in the marketplace for a brand-new phone or cell carrier, or are interested for any factor in cell phone networks, chances are you’ve run into the acronyms CDMA and GSM. You may be questioning what exactly are GSM and CDMA, and how do they affect your phone?
The two cellular standards operate in various areas and allow for worldwide interaction between people, however, each converts incoming and outbound data into radio waves differently. Neither need to be a huge element when purchasing a mobile phone, but one requirement is well-known for tethering you to a carrier while the other is not. Everything depends upon where you are and what you’re trying to find.
In this story we’ll focus on U.S. networks.
CDMA vs. GSM What’s the Difference
Which Carriers are CDMA? Which are GSM?
In the United States, Sprint, Verizon and U.S. Cellular use CDMA. AT&T and T-Mobile use GSM.
Most of the rest of the world uses GSM. The worldwide spread of GSM came about because in 1987, Europe mandated the technology by law, and since GSM comes from an industry consortium. What we call CDMA, by and big, is owned by chipmaker Qualcomm. This made it less costly for 3rd parties to construct GSM equipment.
For call quality, the technology you use is much lesser than the method your carrier has developed its network. There ready and bad CDMA and GSM networks, but there are key differences in between the technologies. Here’s what you, as a customer, have to know.
It’s much easier to switch phones on
GSM networks, since GSM providers put customer info on a removable SIM card. Take the card out, put it in a different phone, and the new phone now has your number. What’s more, to be considered GSM, a provider should accept any GSM-compliant phone. So the GSM providers do not have total control of the phone you’re using.
That’s not the case with CDMA. In the U.S., CDMA carriers use network-based white lists to confirm their subscribers. That suggests you can just change phones with your provider’s authorization, and a provider does not have to accept any specific phone onto its network. It could, but normally, U.S. carriers select not to.
Lots of Sprint and Verizon phones now have SIM cards, however that isn’t because of CDMA. The SIM cards are typically there for Sprint’s and Verizon’s 4G LTE networks, due to the fact that the LTE standard likewise uses SIM cards. The phones may likewise have SIM slots to support foreign GSM networks as “world phones.” But those providers still use CDMA to validate their phones on their own home networks.
3G CDMA networks (called “EV-DO” or “Evolution Data Optimized”) likewise, normally, can’t make voice calls and transfer data at the same time. Again, that’s an available option (referred to as “SV-DO” for “Simultaneous Voice and Data Optimization”), however one that U.S. carriers haven’t adopted for their networks and phones.
On the other hand, all 3G GSM networks have simultaneous voice and information, due to the fact that it’s a necessary part of the spec. (3G GSM is also in fact a type of CDMA.)
So why did so many U.S. carriers opt for CDMA? Timing. When Verizon’s predecessors and Sprint changed from analog to digital in 1995 and 1996, CDMA was the newest, most popular, fastest technology. It provided more capacity, better call quality and more prospective than the GSM of the day. GSM captured up, however already those carriers’ courses were set.
It’s possible to change from CDMA to GSM. Bell and Telus in Canada have done it, to obtain access to the broader variety of off-the-shelf GSM phones. However Verizon and Sprint huge enough that they can get custom phones developed for them, so they do not see the have to lose money changing 3G innovations when they might be constructing out their 4G networks.
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The Technology Behind CDMA vs. GSM
CDMA and GSM are both multiple gain access to innovations. They’re methods for individuals to cram multiple phone calls or Internet connections into one radio channel.
GSM came first. It’s a “time department” system. Calls take turns. Your voice is changed into digital data, which is given a channel and a time slot, so three get in touch with one channel appear like this: 123123123123. On the other end, the receiver listens only to the appointed time slot and pieces the call back together.
The pulsing of the time department signal developed the infamous “GSM buzz,” a buzzing noise whenever you put a GSM phone near a speaker. That’s primarily gone now, because 3G GSM isn’t a time division technology.
CDMA required a bit more processing power. It’s a “code department” system. Every call’s data is encoded with a special key, then the calls are all sent at the same time; if you have calls 1, 2, and 3 in a channel, the channel would just state 66666666. The receivers each have the special key to “divide” the combined signal into its private calls.
Code division turned out to be a more effective and versatile innovation, so “3G GSM” is in fact a CDMA technology, called WCDMA (wideband CDMA) or UMTS (Universal Mobile Telephone System). WCDMA needs larger channels than older CDMA systems, as the name suggests, however it has more data capacity.
Considering that its beginning, GSM has actually evolved faster than CDMA. As I discussed above, WCDMA is thought about the 3G variation of GSM innovation. To even more speed things up, the 3GPP (the GSM governing body) released extensions called HSPA, which have sped GSM networks approximately as quick as 42Mbps, at least in theory.
Our CDMA networks, on the other hand, are stuck at 3.6 Mbps. While faster CDMA innovations exist, U.S. carriers picked not to install them and have instead relied on 4G LTE to be more suitable with international standards.
The Future is LTE
The CDMA vs. GSM gap will close eventually as everybody relocates to 4G LTE, however that does not mean everyone’s phones will be compatible. LTE, or “Long Term Evolution,” is the new globally accepted 4G wireless standard. All the United States carriers are turning it on.
The problem is, they’re turning it on in various frequency bands, with various 3G backup systems, and even, when it comes to the brand-new Sprint Spark network, using an LTE version (TD-LTE) that doesn’t deal with any other U.S. provider’s phones. There are very few phones that support all the carriers’ LTE bands.
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A growing number of phones support all these requirements, but it can be hard to tell which ones. The iPhone 6, the iPhone 6 Plus and the Google Nexus 6 are the most flexible. iPhone 6 and 6 Plus systems from AT&T, T-Mobile, and Verizon can all be used on all three providers, however they do not have Sprint’s special LTE bands. Sprint iPhones have all the bands, however Sprint has stringent opening policies. Nexus 6 phones will technically deal with all four providers, however Sprint only allows phones purchased from Google or Sprint on its network.
HTC One (M8) and Samsung Galaxy S5 phones from Verizon will work rather on AT&T’s and T-Mobile’s networks, albeit with minimal protection due to the fact that while they have CDMA, GSM and LTE, they do not have all the frequency bands AT&T and T-Mobile use. Versions of those same models sold by AT&T and T-Mobile will not deal with Verizon at all, because they lack the CDMA radio required for Verizon. It’s a mess.
So what does all of this mean for you? If you wish to change phones typically, use your phone in Europe, or use imported phones, just go with GSM. Otherwise, choose your provider based on protection and call quality in your area and presume you’ll most likely need a brand-new phone if you switch providers. Our Readers’ Choice and Fastest Mobile Networks awards are an excellent place to begin.
Is One Better Than The Other?
If you’re a U.S. consumer and questioning what companies use which type of network, the split is right down the middle: AT&T and T-Mobile are GSM providers, while Verizon and Sprint are CDMA. In reality, picking a brand-new phone or provider exclusively based upon GSM, CDMA, or LTE doesn’t necessarily matter, as what services, features, phones, and service quality a network offers aren’t solely dependent on their network infrastructure. So, unless you have a specific need for selecting among the other, choose the provider that best fits your tastes, needs, and spending plan.