some devices dose not support font engine to show farsi  text , u should use "bit
map" font , i had the same problem  , and i used that.
2 way for u:
method-1-implement a font component for drawing farsi text  by implementing a
class that have 3 main method
1-drawString(Graphics g,String text,int x,int y,int anchor);
2-stringWidth();
3-fontHeight();
method-2-using an open source project of this implementation if u can find it ,
use this link
"forum.gsmaria.com/attachment.php"

I found an application  
on j2me.blogfa.com named patchedFontME.
This application solved my problem  on SonyEricsson
mobiles but the problem is still exist in some other
mobiles like Nokia.

Your solution  is suitable for Canvas but I want to use
Farsi (Persian) text  inside standard components like
Alert, List, ChoiceGroup and so forth. These components
just get a String object as their argument. What should
I do? I am using j2me  Polish 2.1.1.

My code:

//#style mainScreen
screen = new List(Locale.get("menu.title"), List.IMPLICIT);

//#style mainCommand
screen.append(Locale.get("menu.start"), null);

Locale.get("...") returns a Java String object.

make messages_persian.txt (just like messages_english.txt in polish)write youre persian message in unicode format there(u can use this for dynamic localization too)