AAre you using a special font? Could you try typing this letter with its ASCII code?
I use droid-serif font.
When I use Arial it's ok, so probably it's because of the font?
Are there any chances to change the substitute font?
Because windows phone doesn't display my font. It changes to another, so it would be great set good font replacement
You are probably right about that. I am not sure what substitute you could use but there are ways to sort font by styles and types and compare them.