I installed Russian fonts an I have good news. If I create database with
character set WIN1251, I can use Russian letters :)
bad news is that in there I can use Russian and English letters only.

But I also need to use in same database English and Baltic (õäüöÜÖÄÕ)
characters.
So I created a test database with character set ISO8859_1 and created
some fields with character set WIN1251.
like this

CREATE DATABASE localhost:testdb.gdb
USER SYSDBA
PASSWORD masterkey
PAGE_SIZE 4096
DEFAULT CHARACTER SET ISO8859_1;

CREATE TABLE TEST (
TEST_ENG VARCHAR(50),
TEST_RU VARCHAR(50) CHARACTER SET WIN1251,
);


when enter data to Field TEST_ENG everything is OK.
When I enter Russian characters into TEST_RU I get error message:

Arithmetic overflow or division by zero has occurred.
arithmetic exception, numeric overflow, or string truncation.
Cannot transliterate character between character sets.



any ideas?