Character Sets
UTF-8 is widely supported on XHTML compatible handsets, with the exception of SSL pages on old KDDI phones.
au
To use xhtml with utf-8 for au, you need to set the content type to be
text/html; charset=utf-8
as opposed to the standard
application/xhtml+xml; charset=UTF-8
If you don't do this, the text will appear as mojibake.
Font Issues
There are some kanji that do not display on all phones, but have an equivalent character that does. For instance, 髙 does not display on some phones, but 高 does. If you are generating your own content, you should stick to the standard kanji. However, user generated content might include the alternate forms, in which case you should map them using the strategy described in this blog entry.
Character Entities
Non-breaking space as a character encoded as Hex 00a0 will not display properly on docomo phones (F-08A tested). Other forms such as and   work properly.
– (–) will not display properly on most phones
· (·) is displayed properly on utf-8 pages on most phones. Exceptions are: F-08A
