XML Application

[lunacom]

We're developing a XML application that manage a shared address book.

We have encountered a problem:
The idea is to obtain the name of the caller by interrogation of our address book.

We’re trying to do it by setting in "incoming call" on "action url" an URL that have to return an XML of type "IPPhoneTextScreen".
But it doesn't work, the phone ignoring the passed XML.

Do you have any suggestion?
Can we do it without a LDAP server?
Regarding this will be released updates?

Thanks
Lunacom