Basic Cell Phone Acronyms You Need to Know

Confused by the alphabet soup of cell phone acronyms? I don't blame you. Here's a cheat sheet that'll help you navigate the waters while your shopping for your next phone—or trying to get the most out of the handset you've got.

Most of the confusion arises when it comes to the various types of cell phone networks. For example, when I ask my aunts and uncles which networks their phones work on, they'll usually tell me their carrier instead of whether they're using GSM or CDMA—and frankly, before I started writing about cell phones for a living, I didn't know the difference, either. So first, let's start with a quick overview of the two main standard for cell networks:

• GSM: Short for Global System for Mobile Communications, GSM is the most widespread standard for cell phones networks in the world. If you're a jetsetter who likes keeping in touch during your far-flung travels, you should go with a GSM-enabled phone, and here in the U.S., AT&T and T-Mobile are both GSM carriers. Besides the technical differences between CDMA and GSM networks (I'll spare you the details), the main distinction of a GSM phone is that it comes with a SIM (Subscriber Identity Module) card—a little plastic chip that, as its name implies, identifies your phone on the GSM network. If you take the SIM card out of your GSM phone and put it into another GSM handset, you'll be able to place and receive calls on the second phone using your own cell phone number. GSM phones are also capable of handling six-way conference calls.
• CDMA: Short for Code Division Multiple Access, CDMA networks are much more prevalent in the U.S. than they are abroad, and while CDMA boasts many of the same features as GSM networks (including caller ID, call waiting, and text messaging), there are some key differences—namely, CDMA phones don't use SIM cards. Instead, your phone's identity and number are programmed into the handset by your carrier, and you can't easily switch numbers on CDMA phones as you can with SIM-equipped GSM phones. Also, CDMA phones can only handle three-way conference calls, versus six-way calls on GSM networks. Major CDMA carriers in the U.S. include Sprint, Verizon Wireless, and regional operator Alltel.

OK, so you've got your two main flavors of networks, but now I'm going to stir another variable into the mix: 3G. Here's the deal: GSM and CDMA are both considered second-generation, or 2G, networks (the first generation being AMPS, an analog network used mainly back in the 1980s). Unlike the old voice-only AMPS networks, digital GSM and CDMA networks can handle both voice and data calls, which means you can send text messages, surf the Web and get caller ID info. But data flows slowly over GSM and CDMA—think dial-up, only slower. Streaming video and music? Forget it.

That's where 3G, or third-generation networks, come in. These so-called 3G systems allow data to flow at speeds you'd expect from a home DSL modem or better—and at those speeds, you get features like streaming video and full-track music downloads. The main types of 3G networks include:

• EV-DO: An add-on for CDMA networks, EV-DO (or Evolution-Data Optimized) delivers data speeds between 144Kbps to 2Mbps to CDMA cell phones, perfect for streaming video and music. Sprint offers EV-DO access through its Power Vision phones (which are typically a little pricier than standard models); on Verizon Wireless, look for the "V Cast" label.
• UMTS and HSDPA: Both UMTS (Universal Mobile Telecommunications System) and HSDPA (High-Speed Downlink Packet Access) are upgrades to GSM networks, and like EV-DO, they provide DSL and cable-like data speed. The only difference between UMTS and HSDPA (besides the technical nitty-gritty, of course) is that HSDPA is even faster than UMTS; for that reason, HSDPA networks are often called 3.5G rather than just 3G. In the U.S., only AT&T offers UMTS and HSDPA networks. (T-Mobile is busy working on its own HSDPA network, which should begin going online by the end of the year.)

Somewhere between 3G and 2G lies, naturally enough, 2.5G networks, which give you data speeds that are slightly faster than dial-up—no good for streaming video, but fine for messaging or mobile Web browsing. These networks include:

• 1xRTT: A variant of the CDMA standard, 1xRTT (or "1 times Radio Transmission Technology") gives you data speeds between 30Kbps and 90Kbps, a bit better than your typical 56Kbps dial-up modem. Most of the non-3G phones on Sprint and Verizon have 1xRTT capabilities.
• GPRS and EDGE: The 2.5G flavors of GSM networks, GPRS (General Packet Radio Service) and EDGE (Enhanced Data Rates for GSM Evolution) also give you data in the 30Kbps to 90Kbps range, with EDGE running slightly faster than GPRS. Again, most of the non-3G phones on AT&T offer either GPRS or EDGE, while T-Mobile—which has yet to launch a 3G network—only does GPRS and EDGE.

Whew! That's a lot of terminology, I know—and believe it or not, I've barely scratched the surface. I'll tackle more wireless acronyms in future posts; in the meantime, if you're curious about the technical details of the various cell networks, I'd suggest combing through Wikipedia, or check out Phonescoop's exhaustive glossary.

Related:
Cellular networks [Wikipedia]
Wireless glossary [Phonescoop]