Demystifying mobile phones and plans: GSM vs. CDMA

This is the first in a series of articles about mobile phones and plans.

Just like there are AM and FM radio waves, aka bands, there are two mobile radio wave standards, or bands, in use in our country: GSM and CDMA. The important thing is that there are two bands and not what the acronyms stand for. Keen readers and geeks alike will point out that the word “band” is used slightly in a different manner when talking about the mobile phone industry but to keep matters simple, we’ll ignore that it is used differently.

If rock 'n' roll is your favorite music genre, you can tune your radio to 100.7 WMMS or 98.5 WNCX stations on the FM band to get your fix. For traffic reports, news and sports news during your daily commute, you may tune to WTAM 1100 on the AM band.

Like WMMS and WNCX in the FM band, or WTAM in the AM band, analogy here is that we have T-Mobile and AT&T using the GSM standard while Verizon and Sprint are using the CDMA standard.

MetroPCS, Virgin Mobile, Cricket and others – mobile operators, called MNVOs, who resell service from the major carriers – also fall under GSM or CDMA standards. Why? MVNO service providers do not have their own transmission towers but instead share the infrastructure of the big four carriers due to a federal mandate initiated to provide options and competition. To that end MVNOs may offer cheaper service plans, through comparative compromises to what the big boys offer, that may or may not affect you depending on your use case.

Cell phones and smartphones that you buy from, or to use with, GSM-based carriers cannot be used, in most cases, with CDMA carriers. Although the newer “LTE” band has been evolving as a third standard nicely with smartphones’ use of mobile data while being agnostic to GSM/CDMA and embraced by both, technical reasons beyond the scope of this column make LTE half baked until they evolve some more.

Make no mistake – the above is only a discussion about whether a GSM phone can be taken to a CDMA carrier, and vice versa, and operate at full functionality. (The answer is, in most cases, no or with crippled functionality.) Phone calls you make/receive, texts and apps you use are carrier agnostic meaning it doesn’t matter which carrier you are with; all those will work fine and across networks.

This information is good to know if you were wondering why there are so many service provider options out there and everyone selling similar, if not the same, models of smartphone.

In practice, more than whether they are GSM or CDMA based service providers, your use case should be driving your decision making. Questions such as: quality of reception in your home and where you frequent, how you are going to use your smartphone, what is your monthly budget, and understanding how long a typical smartphone lasts are important. In our next issue we will tackle these questions … stay tuned!

Tak Sato

Strategist and technologist with over 25 years of experience. Holds Bachelor of Science in Computer Information Science and Executive MBA from Cleveland State University.

As Founder of the Center for Aging in the Digital World, a 501(c)(3) nonprofit empowering seniors with digital literacy, Tak connects the dots to help people utilize appropriate technology in their personal and professional lives.

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Volume 10, Issue 18, Posted 10:04 AM, 09.18.2018