Family on the Phone

If you use a cell phone, you may have heard the terms GSM and CDMA. Have you ever wondered what those terms meant?

Here’s just a brief overview of these terms and what they mean to you practically as a cell phone customer. If you are interested in all the technicalities, I am including some links for additional information.

In the world of mobile phone networks, there are two major players. CDMA and GSM.

CDMA: Code Division Multiple Access (CDMA) This network technology was developed by Qualcomm in the United States. It is currently the dominant type of network in North America.

GSM: Global System for Mobile communications This type of network technology was invented in 1987 by the GSM Association. This international organization has dedicated itself  to developing the GSM standard worldwide.

If you do not know which type of network your current cell phone provider utilizes, you can go to this page on Wikipedia to find out.

For all practical purposes, it doesn’t really matter which type of network your cell phone service provider is using. You can make calls, check e-mail, send pictures, surf the web, etc. on both types of networks and you would probably never know the difference in most circumstances. However, for those of you curious souls out there, here are a few differences you might like to consider the next time you are in the market for a nhew cell phone plan.

Differences between CDMA and GSM

Coverage

Many areas only have one type of network or the other available. If you live in an area where you actually have a choice between these two types of networks, check coverage maps to see which offers the best coverage in areas that are important to you.

For instance, where we live, we can choose between either CDMA or GSM.  In our neck of the woods however, the GSM service providers have the best coverage in the cities and along the major highways.  Since my husband travels into the boonies to fix computers for some of his clients, we need the expanded coverage in the rural areas offered by the CDMA provider.

Data transfer speed

CDMA service typically has faster rates of data transfer speed. Optimally, you should be able to get download speeds comparable to a standard DSL connection on a CDMA network. GSM data transfer rates are only about one-fourth of this speed. Technology is currently under development to improve the speed of GSM networks however.

SIM cards

SIM stands for Subscriber Identity Module. The removable SIM card allows phones to be instantly activated, interchanged, swapped out and upgraded, all without carrier intervention. User information , the contact list, and other information is stored on the card rather than on the phone. The SIM itself rather than the actual phone is tied to the network. Phones that are card-enabled can be used with any GSM carrier  In the United States, SIM cards are currently only available on GSM phones

Although there is a type of this card for CDMA phones called a RUIM (Removable User Identity Module), the use of these cards in North America is currently very rare.

For the most part, CDMA carriers in the U.S. require specific phones and equipment that is linked to only one carrier and are not card-enabled. To upgrade a CDMA phone, the carrier must deactivate the old phone then activate the new one. The old phone becomes unusable unless it is re-activated.

Roaming

Currently, CDMA networks offer greater coverage in rural areas of the United States  than do GSM networks. At the same time, GSM may offer a wider “roam-free” zone in some areas than CDMA

International calling

If you do a lot of traveling outside of the United States, you should probably consider using a GSM network. You may even be able to use your existing GSM phone in other countries if it is a 850/900/1800/1900 MHz quad-band phone.

GSM networks definitely have a wider worldwide support for international roaming. Since many GSM phones use SIMM cards, it is possible to purchase a SIM card with pre-paid minutes and a local number in the country you are traveling in. This would prevent additional roaming charges from your carrier back home. Since most CDMA phones do not use SIM cards, this is not an option.

Dropped calls

While doing the research for this post, I read up on and tried to understand exactly how each of these networks allocates bandwidth and time to each cell phone customer using it’s network. Needless to say, it gave me a headache. J So, without getting into all the mind-boggling details, I will simply say that CDMA network towers can handle more calls at once  while GSM networks seem to have a higher rate of dropped calls.

So What’s the right choice?

When you are researching your cell phone options, I personally think some of the most valuable information can be gathered from your local friends and neighbors who use cell phones. Ask them about their experiences and take note of what they say. I’d take the word of real people on the street any day over an internet ad, catchy commercial, or even a salesperson (and I have nothing against sales people). The key is to ask LOCAL people because they will clue you in on local issues with their providers.

More Information

This has only been a very brief description of a very complicated topic. Is it all as clear as mud? If you would like more details, grab the closest bottle of Excedrine and visit the following links.

This site is a great place to start your research.

Wise Geek has a good article about this subject as well.

photo credit: kalleboo

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