Question : Voice Chat Software for LAN

I need a Software that can be able to do following tasks :-

Requirement is only for LAN

1. Connect to any machine on LAN for Voice Chat. (Like yahoo messenger does on WAN)
2. Should work without Internet
3. User will select the second party by IP or MAchine Name.
4. Good if One to Many Broadcast is available.

I can install software's client in all system on my LAN.

Suggest....

Answer : Voice Chat Software for LAN

Netmeeting. Comes with every flavor of Windows except Vista.
You have to install it on XP, but it is there.
   going to start --> run --> conf