I still can't fix the problem... Its strange but when I first configured extensions and filled description in Cyrillic it was ok but after update all Cyrillic text became Cp1252.
Then I've tried to view backup of asterisk db and found corrupted Cyrillic description in devices table. So I dropped table, converted description text in INSERT statement of backup, recreated table and executed insert statement with fixed text descriptions. In asterisk db everything looks fine now but the corrupted description is still displayed in Issabel UI.
Statement before fix:
INSERT INTO `devices` VALUES ('101','sip','SIP/101','fixed','101','ВаÑилий',''),('102','sip','SIP/102','fixed','102','Евгений',''),('103','sip','SIP/103','fixed','103','Егор',''),('104','sip','SIP/104','fixed','104','Лена',''),('201','sip','SIP/201','fixed','201','ВаÑилий mobile',''),('105','sip','SIP/105','fixed','105','Маргарита',''),('110','sip','SIP/110','fixed','110','test','');
After fix:
INSERT INTO `devices` VALUES ('101','sip','SIP/101','fixed','101','Василий',''),('102','sip','SIP/102','fixed','102','Евгений',''),('103','sip','SIP/103','fixed','103','Егор',''),('104','sip','SIP/104','fixed','104','Лена',''),('201','sip','SIP/201','fixed','201','Василий mobile',''),('105','sip','SIP/105','fixed','105','Маргарита',''),('110','sip','SIP/110','fixed','110','test','');
Please I needhelp for further investigation....