NTT DoCoMo first introduced i-Mode in Japan in February
1999. Since then it has been immensely successful. There
were more than 20 million users by March 2001. Despite the
fact that i-Mode does not yet exist outside of Japan, i-Mode
accounts for over 60 percent of the world’s mobile Internet
users! There are over 1,500 official Web sites and over 40,000
independent sites. In fact, i-Mode Web sites may be built anywhere
in the world and many times are included with HTML
Web server sites by placing the code in a subdirectory.
i-Mode is a client–server protocol similar to WAP and illustrated
in Figure 2-10. It allows users to navigate a series of
menus on their phone display in order to access Internet content
on i-Mode sites.
One very important comment must be included here about
i-Mode. NTT DoCoMo created i-Mode as a proprietary protocol
without international standards’ body cooperation. The
result is a tightly controlled application environment that NTT
DoCoMo designs and markets to their best advantage. It should
also be noted that DoCoMo is one of the first carriers to offer
usage-based billing for i-Mode. Because i-Mode is packetbased,
they charge for the actual volume of data transmitted.
i-Mode phones in Japan operate on the Personal Digital
Cellular (PDC) network, which is very similar to the North
American TDMA network. Therefore, the data rate is limited
to 9.6 Kbps. In the future, when W-CDMA is launched in
Japan, much higher data rates will become available.
Although i-Mode can only be used on phones inside
Japan, NTT DoCoMo clearly intends to make it a world standard
for Web browsing on wireless devices. Their recent
investment in AT&T Wireless, the agreement giving AT&T
access to i-Mode technology, and the purchase of an ISP—
Verio Communications—demonstrates that they will be very
proactive in advancing i-Mode throughout the world. They
have also taken a 15 percent stake in Dutch KPN Mobile and
claimed 20 percent of Hutchison 3G.
Unlike WAP, which uses WML as its markup language,
i-Mode services are built using i-Mode-compatible HTML,
referred to as compact HTML or c-HTML. On the surface,
both look very similar and in fact, both markup languages have
common elements. An example of i-Mode code is shown in
Figure 2-11. It looks just like HTML to the seasoned Web programmer
with the exception of the accesskey command.
Unlike WAP, there is no card deck, but i-Mode does support
color displays.
DoCoMo based i-Mode on a subset of HTML 2.0, HTML
3.2, and HTML 4.0 specifications with i-Mode specific extensions.
These extensions include tags that have special meaning
on a cellular phone such as the tel: tag, which is used to hyperlink
a telephone number. By clicking on the link, users can
place a call to the number.
Just as in WAP, some i-Mode phones support more than the
basic standard protocol. Features that require cursor movement
in two-dimensions, such as tables, are not supported.