Do not eat your SIM card
- the misconceptions surrounding international mobile phones
If we are all such savvy travellers - well versed in the incompatibilities between mobile phones
in Japan and rest of the world - why is it that certain companies selling and renting GSM services
to the Japanese still feel the need to warn them not to eat their SIM card?
It is an extreme example, true, but it is happening. Is this over-caution on behalf of the phone
companies, or are travellers still not as clued-up about the different mobile phone technologies as
they like to think?
Listening to the questions that Mobell Communications, the international phone company, are still being
asked by people travelling both to and from Japan, it would seem the second conclusion is closer to the truth.
The issue of incompatibility between phone technology in Japan and the rest of the world has been further
confused in recent times with the advent of new technology. When once your Japanese phone would not work
outside of Japan, and your international phone would not work in Japan, the boundaries are becoming blurred.
Certain phones now exist that can be used both inside and outside Japan.
Reading this article should hopefully give you a general overview of mobile phones in Japan today, and how
they affect your choice of services if you are travelling internationally.
SIM Card ?
SIM card is a Subscriber Identity Module card - a small printed circuit board that must be inserted in any
GSM-based mobile phone when signing on as a subscriber. It contains subscriber details, security information
and memory for a personal directory of numbers. The card can be a small plug-in type (about the size of a large
man's thumbnail) or sized as a credit-card but has the same functionality. The SIM card also stores data that
identifies the caller to the network service provider. It tastes terrible.
You say dual-mode, I say dual-band
Often the first stumbling block for people trying to understand the different mobile phone standards in the world
is the terminology - especially between the terms "mode" and "band" when referring to handset technology.
The "mode" refers to the fact that the phone supports a type of technology - like GSM (Global System for Mobile
communication) or WCDMA (Wideband Code Divisional Multiple Access). Thus a dual-mode phone uses two different
types of technology in one handset.
The "band" part refers to the number of frequencies on a single technology that a phone uses. For example, a
dual-band phone might work on both GSM 900MHz and GSM 1800MHz. Phone handsets can currently range from single to
It is also possible that phones can be both multi-mode and multi-band. For example, a phone could work on GSM 900MHz
and GSM 1800MHz, while also working on WCDMA.
The Japanese mobile phone situation...
Very briefly, there are three mobile phone technologies supported by the major networks within Japan - PDC (Personal
Digital Cellular), CDMA (Code Divisional Multiple Access) and WCDMA. DoCoMo, Vodafone and TU-KA support the established
PDC, and DoCoMo and Vodafone have also introduced the newer WCDMA, while AU supports CDMA. All three of these
technologies are incompatible with each other.
Outside of Japan, CDMA networks exist in about 40 other countries, but by far the most common technology in the world
is GSM - which exists in over 200 countries (including major destinations in Europe, Africa and Asia Pacific). Within
these countries, GSM uses four different frequencies - 850, 900, 1800 and 1900MHz.
The Japanese networks have looked to combine international CDMA, or GSM technology, with their domestic technology as a
way to offer a service to their subscribers that allows them to use just one phone both in Japan, and internationally.
One of these major networks currently offers a service that works on a dual-mode handset, combining WCDMA in Japan, and
GSM internationally. Another offers the FOMA Card, which can be easily removed from the handset and when inserted into a
foreign handset, can be used abroad. These foreign handsets are presently not available but are expected to be released
before the end of this year.
The other main service provider offers an international service on its Japanese CDMA phones that also allows the phone
to be used on the CDMA networks in Korea, Guam, Saipan, Thailand, China, Hong Kong, America, Australia, New Zealand and
Canada. Out of these, data transfer is only possible in Korea.
...and its limitations
However both WCDMA/GSM and international CDMA have their limitations.
Switching to dual-mode WCDMA/GSM phones should be popular in Japan as they allow users to keep their Japanese number abroad,
and keep their own up-to-the-minute, all-singing-all-dancing mobile phone handset - rather than switching to a second less
modern phone with a different number to use overseas.
However, despite the obvious benefits of dual-mode WCDMA/GSM phones, many people have not taken to them yet as the WCDMA
coverage within Japan is still limited to major cities - by March 2004 only 3 million people had signed up to 3G in Japan
(BBC News), this is not much when you consider that there are over 80 million mobile phone subscribers in Japan today.
Japanese users are still finding that their older, single-mode PDC phones offer better coverage within their home country.
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