I find this answer in web and hope it be usefull:
"The codepage 65001 does refer to the UTF-8 character set. You would
need be make sure that your asp page (and any includes) are saved as
UTF-8 if they contain any characters outside of the standard ASCII
character set.
By specifying the CODEPAGE attribute in the <%@
block you are indicating that anything written using Response.Write
should be encoded to the Codepage specified, in this case 65001 (utf-8).
Its worth bearing in mind that this does not affect any static content
which is sent verbatim byte for byte to the response. Hence the reason
why the file needs be actually saved using the codepage that is
specified.
The CharSet property of the response sets the CharSet
value of the Content-Type header. This has no impact on how the content
my be encoded it merely tells the client what encoding is being
received. Again it is important that his value match the actual encoding
sent."