The call monitoring feature not working in XP machines, but the same works in Vista. I have checked the NIC Card, both has got the same intel nic and drivers are also match each other. I have tried couple of XP Machines, no joy. I tried the registry editing, monitormodeenabled, etc... But none of them work. When i Sniff the packet i can see the RTP Stream, i can extract the RTP packet alone and i can hear the voice. But when i do live monitoring i see no error message, and it is blank... Any suggestions. Thanks in advance.