Does not support sending char with double byte

I cannot use "Conversation" reply message by the converation box if the char that I typed in with double byte.

Eg. Special Char, Asian Char etc...

I could type double byte char, and it shows the char normally. But the receiver will not see any char but many question marks.

This happened with any S60 3rd device. And I'm using N73 and N96 with latest Hong Kong firmware.