Using a Cell Phone Internationally

Will you want to use your mobile phone while you're traveling? Probably. But you'll need to prepare before getting on the plane. There are a few issues you'll need to consider, such as what country you're traveling to, which carrier you're using, what kind of phone you have, whether it has a SIM (Subscriber Identity Module) card, and whether there are any potential security issues to worry about.

Differences among countries

If you're an American traveling to Europe, you'll find that staying connected via your mobile phone is easier if you have a GSM (Global System for Mobile) phone. Those already using a GSM-based providersuch as T-Mobile or AT&Tneed to have a three-band GSM telephone. The same is true if you live in Europe and you're traveling to the U.S., because there is more than one flavor of GSMin fact it gets very complicated very quickly when you start looking at which countries use which frequencies. As a rule of thumb, North America and Central America are on GSM 1900 MHz, while most of the rest of the world is either on 900 or 1800 MHz or a combination of both. There is a list of all countries and their related GSM frequencies in Appendix A.

Traveling to Japan often means you should plan on renting a mobile phone that works with their 3G system or else be somewhat disconnected. (Japan is not on the GSM 900, 1800, or 1900 systems.) The problem with relying on Japanese local phones is that the instructions are in Japaneseunless you're able to read kanji, it's quite a puzzle trying to figure things out, not to mention the fact that the network operators and voicemail prompts are all in Japanese.

Fortunately, all is not lostif you're a Vodafone customer, anyway. Vodafone has extended its network and roaming agreements into Japan. For Europeans currently using Vodafone as your carrier, it's a simple matter of renting a 3G phone in Japan and inserting your Vodafone SIM card into it. Of course, as I said before, you will be charged international roaming fees. But hey, you'll be connected, and you'll be using your own phone number…in Japan!

For intrepid readers who want more information on how to use Japanese pay-phones, see www.yesjapan.com/culture

For Americans with Sprint PCS, you won't be able to make calls using your phone outside of the United States. In fact, the last time you'll be able to use your Sprint PCS phone is just before the flight attendant says, "Please turn off any unapproved electronic devices."

Differences among carriers

Your carrier may or may not have international roaming agreements with the local carriers in other countries. Or it might be using a network that does not permit international roaming (for example, CDMAsee the chart on page 11). A week or more before you fly, call your carrier and inquire about its international service plans and roaming agreements. This short phone call could save you hundreds of dollars in roaming and long-distance fees.

GSM and rental phones

If you have a three-band GSM phone that works on GSM 900/1800/1900 networks, you're already able to travel to many other countries with your own phone and your own telephone number. If you don't have a GSM phone that works outside your country, then you'll need to rent a mobile phone either before you leave or when you arrive in your destination country. Lots of companies offer international phone rentalssome of the better-known ones are Telestial, Inc. (www.telestial.com) and Cellular Abroad (www.cellularabroad.com).

Swapping SIM cards

The next thing to consider is whether or not your phone has SIM capability. A SIM card is a little microchip that contains all the information (account information, codes, and so on) that your phone needs to make and receive calls. The beauty of the SIM card is that it is tinyroughly the size of your thumbnailand it is removable. In many countries, you can buy a second SIM card from a local carrier and use it while you're traveling to make local calls without incurring local or international charges. Using a "rented" SIM will give you a local phone number, but bear in mind that anyone calling you from the U.S. will incur international calling rates instead of the domestic rate they incur when calling your U.S.-based number. And don't lose your original SIM card! However, before you can use another SIM card in your phone, you need to contact your provider for instructions on unlocking your phone.

This is what a typical SIM cardlooks like, and is roughly the actual size.

Unlocking your phone

The way cell phone service works is that the electronic serial number (ESN) in your phone acts like a digital fingerprintit identifies you to your carrier and tells it what phone you're using. With the ESN, the carrier can determine that your phone's serial number is in fact your phone and therefore knows to send calls to it when someone dials your number.

Buying a SIM card

When you arrive in your destination country, you might be able to buy a local SIM card in a telecom shop. What you want is a "pay-as-you-go" plan and not a month-to-month plan. These plans are offered by such international carriers as T-Mobile, Virgin Mobile, Vodafone, and Orange. You'll pay a .at fee for your cardthis purchase typically includes your local phone number, a few minutes of air time, a voicemail box, and text messaging. After you use your start-up time, you can continue buying bulk minutes of air time that enable you to use your phone like a wireless phone card, while still being able to use the features that are built into your personal phone.

If you're concerned about .nding a SIM card at your destination, you can also buy one (or even an unlocked GSM phone) before you leavetry some online services such as www.telestial.com or www.cellularabroad.com. Both of these companies sell SIM cards for a variety of countries (including the local voicemail features) and they offer a wealth of travel tips, as well.]

By contrast, a GSM phone is not directly linked to you. Instead, its SIM contains the unique ESN, and so the SIM identifies you to the wireless provider. The really cool thing about this is that you can put your SIM into most compatible GSM phones, because pretty much all current GSM phones are compatible with all current SIMs. Separating SIM circuitry from the phone hardware makes all sorts of things possible. Your wireless carrier doesn't give a hoot if you've changed phonesall it cares about is where to find your SIM. Your phone and SIM card are like a car and driver: The car is merely an empty shell without a driver, waiting to go somewhere. Slip a driver into that car, and suddenly transportation becomes possible. The same is true with SIMs and phonesslip that card into a phone, and suddenly you have communication power in your hands.

But there may be a catch: Many wireless providers lock their phones, meaning that their phones are programmed to work only with the SIMs issued by that company. Reversing that programming so that your phone can work with any SIM is called unlocking. Fortunately, as far as I know, all GSM phones can be unlocked.

If you're lucky, your phone can be unlocked by simply keying a secret code into it. The code is usually a unique number only for that particular phone, based on its serial number (called its IMEI, or International Mobile Equipment Identifier) coded by the service provider who locked it. Though the carrier probably won't unlock your phone for you, they will provide the code for you on request. Additionally, if you Google the phrase unlocking a cell phone, you might find instructions for unlocking your phone for free, as well as many companies that will do it for a fee.

Some types of phones need their firmware (operating system software) to be rewritten to remove the lock. This requires connecting the phone via a special data cable to a special programming unit.

Communications standards

GSM Global System for Mobile communications. Originally developed as a Europe-wide standard for digital mobile telephony, GSM has become the world's most widely used mobile system.

GPRS The General Packet Radio Service is part of the GSM standard. It delivers "always-on" wireless packet data services to GSM customers. GPRS gives you data speeds of up to 115 Kbps. That's twice the speed of your 56 Kbps modem!

TDMA Time Division Multiple Access is an advanced digital cellular platform that converts audio signals into a stream of digital information (made up of 1s and 0s). This is the same thing a modem does: It converts audio into easily transferable digital bits.

CDMA Code Division Multiple Access. This technology was originally developed for military use over 30 years ago. Remember those humongous green brick-like walkie-talkies the soldiers used when they called in air strikes? They were using the same technology that Sprint PCS is using today.

IDEN Integrated Digital Enhanced Network. A Motorola Inc. enhanced specialized mobile radio network technology that combines two-way radio, telephone, text messaging, and data transmission into one network.

3G Third Generation. The term used to refer to the next generation of wireless communications technology, the .rst generation having been analog cellular, and the second generation being today's digital cellular networks.

EDGE Enhanced Data Rates for GSM Evolution. The GSM service EDGE will increase the possible speed for transferring data to 384 Kbps.

SIM A Subscriber Identity Module is a card commonly used in a GSM phone. The card holds a microchip that stores information and encrypts voice and data transmissions, making it close to impossible to listen in on calls. The SIM card also stores data that identi.es the caller to the network service provider.

Security issues

Treat your SIM card and your mobile phone as you treat your wallet or purse. Mobile phones are highly pilferable, valuable items. Keep your eyes on the prize.

If you happen to lose your SIM card, some bad guy (or girl) could potentially grab your card and begin making calls to anywhere on the planet, orif they got their hands on your unlocked GSM phone, they could even toss your precious SIM card into the trash and pop in their own SIM card. If this happens, treat your lost SIM card just like a lost credit card. Call your mobile carrier immediately and let them know what happened. From that point forward, they will not allow any calls to be made from that particular SIM.

If you have a U.S. carrier and happen to be in the U.S. when you lose the card, you can walk into any of your carrier's retail outlets, get a new card, and immediately begin making calls again. If you're outside the U.S., then you'll probably have to "rent" a SIM card until you get back to the States.