Mobile Phones

Do not eat your SIM card - the misconceptions surrounding international mobile phones

keitai denwaAs for using CDMA internationally, there simply aren't enough CDMA networks available outside of Japan; many people still need access to GSM when travelling to most places.

These are the people who then look to buy or rent a GSM international phone to use specially when travelling, and it is at this point that a lot of the misconceptions occur.

Many Japanese travellers are familiar with the services offered by the three service providers, are familiar with terms such as dual-band and dual-mode, and then think that if they buy or rent a GSM phone, they will enjoy the same benefits, such as keeping their Japanese number (this is also the case for many non-Japanese who believe their GSM phone can work in Japan).

At this juncture, consider the opinion of one regular overseas traveller, YA. YA is in his thirties, from Tokyo and frequently travels in Europe.

"Recently, WCDMA technology has allowed the Japanese SIM card to function abroad. However, people I deal with when on assignments abroad often complain, to the tune of 'If you are here, why should I have to call Japan?'"

International GSM mobile phones

The basic truth of it is, if you own a phone that does not work on GSM technology, and you are leaving for one of the 200+ GSM countries, you will need to buy or rent a GSM phone, and be prepared for the fact that they are not as technically advanced as Japanese phones.

There are many companies that now sell and rent international GSM phones in Japan, but before you approach them with your questions, below are five of the most common misconceptions that get said about international GSM phones:

Common misconceptions about GSM phones

1. It is cheaper to rent than buy a GSM phone
Not true - the industry in Japan has traditionally been geared towards rental. This has been a cost efficient method while the prices to buy handsets has been high. Now the price to buy a GSM phone has come down dramatically, and you can often find you can buy the handset and SIM card for less than the cost of rental for your trip. You will then have your own phone and never have to pay for rental again.

2. Local SIM cards are better than roaming SIM cards
Not true - it all depends on what you want from a service. Visit any travel forum and you will find people advising you to get local pre-paid SIM cards for the country that you are visiting. Using local SIM cards you will benefit from local call rates, often meaning free incoming calls. However, the downside is that you will need to constantly top-up your call credit, and change phone numbers each time you buy a new SIM card in a new country.

The other option is relatively new, but you can now subscribe to overseas post-paid services that use one SIM card that works in all GSM countries (providing your handset has the correct frequencies). Previously you had to be a national of the country you were visiting to subscribe to this type of post-paid services. You will pay a little more for your calls, but you will have just one dedicated number, no matter which country, every time you travel. This can be far more convenient than constantly swapping local SIM cards, and worth the slightly higher prices.

3. You can use your Japanese number outside of Japan
Yes and No - as explained earlier, you can only use your Japanese number if you own a dual-mode WCDMA/GSM phone (or a CDMA phone in another CDMA country). If you have brought or rented a GSM phone you will be given a phone number registered to the country of the SIM card. That said, there are services available whereby calls to your Japanese number can be forwarded onto your rental mobile phone. Needless to say, the party receiving the forwarded call will incur an often hefty forwarding charge.

4. Your phone number changes for country you visit
Not true - Each SIM card has just one number. That number will be in the format of the country that the SIM card is registered to, no matter which country you visit. You will only change numbers if you buy local SIM cards in each country, therefore getting a new local number each time.

5. GSM phones work everywhere within GSM supported countries
Not true - just because a country supports a particular GSM frequency, you may find that the coverage does not extend all over the country. In some of the more developing countries, such as those in Africa, you can use your GSM phone in only the largest cities; in the countryside it may be useless.


This article is by no means the final say on the subject of international phones - technology moves fast and information that is true at one time can quickly be made obsolete by the latest innovation or partnership. Hopefully what you will take from this is a clearer understanding of the problems facing Japanese travellers looking to use mobile phones internationally. And if you take just one piece of information from this article, let it be that you should not eat your SIM card.