Enable access to Internal Contacts via XML

In order to enable access to Internal Contacts via XML Service, it is needed to edit following file:
<IAS_INSTALLATION_FOLDER>\Apps\Speedy\Settings\SpeedyPhoneService.config.xml

(Standard IAS installation folder is C:\Program Files (x86)\StonevoiceAS)

Adding the following lines in-between configuration statements: 

<configuration>
<preference key="Speedy.AuthLevel.ShowLocalContacts" value="2" />
<preference key="Speedy.directories.ShowLocalDirs" value="false" />
<preference key="Speedy.directories.ShowDirectoryType" value="false" />
</configuration>

Open a command prompt and execute this command
iisreset