Mobile Phone

Why Mobile Phones are helpful
Along with the obvious convenience and quick access to help in emergencies big and small, mobile phones can be both economical and essential for travelers trying to stay connected. An example: it's not uncommon for mobile calls to be cheaper than local calls made from some hotel rooms. European hotels in particular are known for excessive phone tariffs -- three days of connecting locally at a five-star hotel in Amsterdam once cost me more than $100! However, Europeans have no lock on this practice -- at a hotel in Quito, Ecuador local calls cost USD$.50 a minute! In contrast, many mobile providers offer exceptional plans that include generous amounts of air time, no long distance charges, and in some cases very reasonable international roaming rates.
In other situations, a mobile phone may simply be the only way to get online. This was the case when I stayed at a lovely historic hotel in Krakow's old town -- unfortunately, the ancient phone lines were too noisy to allow a modem connection at any speed. However, thanks to a GSM phone and modem, I could connect with ease.
Why Mobile Phones can be a challenge
Mobile phone usage for the traveler can sometimes be a bewildering affair. This is due to the preponderance of various differing -- and incompatible -- mobile systems, often delineating entire continents or regions. The main systems in use are outlined below. The purpose of this discussion is not to delve much into the technical aspects of each system -- that sort of thing can easily be found elsewhere on the web. Rather, here we'll focus more on where these systems are used and factors important to travelers.
GSM - Global System for Mobiletelephones One of the few mobile phone standards with a self-explanatory name that is actually more or less accurate. It's the closest thing there is to an "international" standard -- GSM systems are used in nearly 200 countries (with 600 million subscribers) worldwide, from Europe (where the standard originated) throughout Africa, Asia and Australasia.
Coverage in these areas is for the most part excellent; in some cities the use of picocells even makes it possible to use phones on moving subway trains. Though a latecomer to North America, GSM is now making some substantial gains there, though with a different flavor than used elsewhere. Originally utilizing the 900 Mhz spectrum, GSM providers in parts of Europe, Africa, and Asia later added additional capacity at 1800 Mhz. In North America, however, GSM service operates at 850 Mhz or 1900 Mhz. The good news for world travelers is that most cell phone manufacturers offer dual-band (900 and 1900 Mhz), tri-band (900, 1800 and 1900 Mhz) and a growing number of quad-band (800, 900, 1800 and 1900 Mhz) phones that will work practically anywhere GSM systems are found.

Example of multi-band GSM "World" Phone
While growing rapidly, in the US and Canada GSM service can be scarce outside of larger urban areas. In Latin America, coverage continues to grow in many countries after it was introduced in Argentina, Bolivia, Chile, El Salvador, Paraguay and Peru (all at GSM 1900) along with Venezuela (GSM 900) and Brazil (GSM 1800). Notable non-GSM countries include South Korea and Japan.
GSM is a feature-rich technology that includes fax capability and SMS (short messaging service). Most providers offer e-mail to SMS gateways, making it possible to receive flight updates and breaking news alerts over the phone. Many providers also offer quick connect data services through ISDN lines, and the latest generation GPRS (Global Packet Radio Service) promises high-speed "always on" data connections much faster than the traditional 9600 bps. If you can't tell, I'm a big fan of GSM and hope that it soon is available everywhere. My principal mobile phone is a tri-band "world" phone with service from T-Mobile, one of the largest GSM providers in the US with roaming agreements with GSM carriers worldwide .
AMPS - Advanced Mobile Phone System At one time, this system might well have been "advanced" compared to earlier methods. The original 800 Mhz analog cellular system introduced in North America in the early 1980s, now it's pretty much technically obsolete. However, even though it's been replaced by newer digital technology, in some rural areas, it still might be the only mobile signal to be had. I often carry a pre-paid AMPS phone as a backup for non GSM-areas. An enhanced version called N-AMPS (Narrowband AMPS) offers some digital phone-like features such as text messaging. Most of the US now uses E-AMPS, for enhanced AMPS. Every country in the Western Hemisphere has 800 AMPS service, as well as American Samoa, Angola, China, South Korea, Lebanon, Nauru, Northern Mariana Islands, Solomon Islands, Turkmenistan, Uzbekistan, and Western Samoa.
D-AMPS - The first digital version of AMPS, also using the 800 Mhz spectrum. Still used (though not widely) in certain countries including Bolivia, Brazil, Canada, El Salvador, Israel, Malaysia, Myanmar, Panama, Russia, Ukraine, Uzbekistan, and Vietnam.
TACS - Total Access Communications Service The original European 900 Mhz analog system launched in 1985 by Vodafone. Still used in Austria, Azerbaijan, Bahrain, Cambodia, China, Democratic Republic of Congo, Gambia, Ghana, Hungary, Ireland, Italy, Japan, Kenya, Kuwait, Malaysia, Mauritius, Nigeria, the Philippines, Singapore, Spain, Sri Lanka, Tanzania, United Arab Emirates, United Kingdom, and Yemen. Uses a protocol known as Frequency Division Multiple Access (FDMA). Variations include ETACS (Extended TACS), ITACS (International TACS), IETACS (International Extended TACS, NTACS (Narrowband TACS and JTACS (Japan TACS).
NMT - An analog rival to AMPS and TACS that uses 450 and 900 Mhz spectrum. Still used in parts of Europe and Asia, including Algeria, Andorra, Bangladesh, Belarus, Bulgaria, Cambodia, Croatia, Cyprus, the Czech Republic, Estonia, the Faeroes, Finland, France, Greenland, Hungary, Indonesia, Latvia, Lithuania, Malaysia, Morocco, Norway, Oman, Poland, Romania, Russia, Singapore, Slovakia, Slovenia, Spain, Swaziland, Sweden, Thailand, Tunisia, Turkey, Ukraine and Uzbekistan. Now that GSM is so widespread, some countries have halted NMT service in the past few years.
TDMA - Time Division Multiple Access The first digital network widely used in the Americas, this is the system which at one time was and still is largely the core of major US wireless networks like AT&T and Cingular. (Of these, however, AT&T and Cingular are now converting some US bandwidth to GSM 1900. They may also use the newer GSM 800, which operates at 850Mhz). Outside the US, TDMA networks can be found in Argentina, Aruba, Bahamas, Belize, Bermuda, Bolivia, Brazil, Canada, Cayman Islands, Chile, China (including Hong Kong), Colombia, Costa Rica, Ecuador, Guam, Indonesia, Israel, Malaysia, Mexico, Panama, Peru, Russia, St. Maarten, Suriname, Uzbekistan and Venezuela. Some industry analysts are forecasting that the increasing growth of GSM and CDMA will eventually signal the end of TDMA. Indeed, it is being phased out so rapidly it may have already have been discontinued in many of the nations mentioned here.
CDMA - Code Division Multiple Access A rival to TDMA in the Americas, this standard was developed by QualComm, from which providers must license its use. CDMA carriers in the US include Sprint PCS (which oddly enough started as a GSM carrier), Alltel, and Verizon. There are now CDMA networks elsewhere in the world, including Argentina, Australia, Canada, Chile, Hong Kong, El Salvador, Guatemala, Israel, South Korea, Peru, Russia, Venezuela and Zambia. This offers some international roaming capability, though nothing like the near-global coverage available from GSM carriers. In the purest technical sense, CDMA is more efficient than GSM. In actual application, GSM has such widespread following and rich features to keep CDMA from being much of a threat. However, it's entirely possible that CDMA will contribute to the eventual demise of TDMA in the Americas, though that time is likely to be many years away for the US and Canada, and much longer for Latin America.
iDEN - (Integrated Dispatch Enhanced Network) iDEN is essentially a hybrid of TDMA digital cell phone and two-way radio. Providers are limited (examples are NEXTEL in the US and Amigo in Israel). Phone equipment is produced exclusively by Motorola, the company that created the standard by blending their historic experience with handheld radios with the expertise in cellular technology. Certain iDEN phones offer GSM 900 compatibility, making global roaming possible in many countries without iDEN networks.
PDC - Personal Digital Cellular Behind GSM and D-AMPS, the world's mostly widely used digital system, though its use is limited to Japan.
PHS - Personal Handyphone System A newer Japanese standard especially designed for high-speed data transmission up to 32 Kbps. Some installations may also be found in parts of China, Thailand and Taiwan.
Satellite Phones
Whether you're posting a breaking news story from the mountains of Afghanistan or just staying in touch with the office during a Caribbean cruise, satellite phones can be the only choice when you absolutely, positively need a phone in the far reaches of the world. Satellite phones can be expensive, though Iridium's $1.50/minute USD charge is sometimes equaled or surpassed by international mobile roaming rates for some GSM carriers. However, only recently have they achieved acceptable speeds for data transmission.
Since there needs to be a clear line of sight between the antenna and satellite, performance can also be affected by poor weather and use is generally restricted to outdoors (though they will sometimes work through glass or canvas). This can also limit the ability to receive incoming calls, though external antenna connections can help overcome some of these limitations.
Also, satellite phones like the Hughes 7100 (shown at right) allow users of the Thuraya system (serving Europe, North & Central Africa, the Middle East, Central Asia and the Indian Subcontinent) to also access local GSM networks in those areas. Other phones offer compatibility with existing AMPS and CDMA networks to help alleviate some of the drawbacks while allowing users to stay connected well beyond the reach of lowly terrestrial networks.
Satellite phone systems are expensive to build and far less competitive than conventional mobile systems, so there are only a few providers to choose from like Iridium, Globalstar, ICO Global, Ellipso, Inmarsat and the previously mentioned Thuraya. Great strides have been made in making these phones increasingly portable, though many of them need an oversized antenna for satellite use.
Satellite Phones

Example of Satellite phone
More to Come
This has been a general overview of mobile phone systems used around the world. I will soon add to the information here with specific tips travelers can use when selecting mobile phone service and options on how to best stay in touch with mobile service while connecting internationally. Please come back soon.