1. The Networks
The first thing to understand is that there are two competing cell-phone technologies in the United States: CDMA and GSM. Each is based on a set of standards that define which frequencies are allowed and how they are used to transmit voice and data. Each also relies on supporting technologies like CDMA2000, UMTS, and HSPA to extend their data capabilities to 3G and 4G speeds. The network you choose will determine which countries in the world you can travel to and still have voice and data coverage.
GSM (Global System for Mobile Communications) is by far the most popular cellular technology, common in most countries outside of Asia, and serving over 75 percent of the world’s cell phone users. In the United States, AT&T and T-Mobile both use GSM, and are able to provide international roaming plans that include coverage in over 150 countries. AT&T’s new global SIM would extend that to over 200 countries.
2. The Phones
The phone hardware you choose makes as big a difference as the network it’s on. Within the GSM standard, each carrier uses different frequencies. Most modern phones are “quad-band”, which should allow cellular reception on any of the GSM-provided networks. Data coverage is another story, as it uses multiple frequencies as well. This can make selecting an appropriate phone difficult since you’ll need to examine the specific frequencies it supports and compare them to those used in the countries you’ll be visiting.
One way to get both cellular and data coverage in as many countries as possible is to purchase a phone advertised as a “global phone” that supports multiple frequencies. The two smartphones that currently offer the best traveling options are Apple’s iPhone 4S or Verizon Motorola Droid 2 Global. Each of these models has versions that support both CDMA and all of the GSM frequencies. Another option is to purchase a dual-SIM phone that can connect to two networks at once.
3. The Tricks
If all you need is mobile data and local calling, a less expensive option is to buy service from a local carrier. As an example, an AT&T user traveling to Spain can purchase service from Orange, a GSM carrier that offers full coverage plans but also provides service on a monthly, weekly or even daily basis. Remove the AT&T SIM card from your phone and replace it with the Orange SIM, and you’ll have local cell and data coverage for far less money than a comparable international plan. You’ll find similar offerings from carriers in most countries.
The Future
Though GSM and CDMA are currently the dominant mobile wireless technologies, a new technology is set to take over. LTE (Long-Term Evolution), an extension of GSM, is being adopted by carriers worldwide and seems poised to become a global standard. Though this could make hardware selection easier, since new hardware would all support LTE, carriers may still add complications by each supporting different frequencies, meaning you may still be limited by which hardware works with each carrier.
Joseph Fieber has 25 years of experience as an IT pro, with a background in computer consulting and software training. Follow him on Google+, Facebook, or Twitter, or contact him through his website, JosephFieber.com.