Mirko, 
I do not believe that the VG224 is a supported voice gateway to be used with CVP. 
(http://www.cisco.com/en/US/docs/voice_ip_comm/uc_system/unified/communications/system/versions/CCMtrix.html)
 
I would guess that it is not a sufficient platform to support the TCL and VXML Applications required for CVP interoperability.