http://maemo.org/community/brainstor...t_in_sms-n900/

As guided from https://bugs.maemo.org/show_bug.cgi?id=7490

User should be able to select the character support "Full" or "Limited".

That's because when you type an SMS in Greek, a character uses more space than typing a Latin character.
By using the Limited character support Greek characters will be automatically transformed in capitals and messages will be sent as of 160 characters each.

For more information please check the above link.