10M users?

CommuniGate Systems has demonstrated a SIP farm supporting 10 million users. The company's All-Active Dynamic Cluster was running on HP Superdome servers; other participating vendors included Intel, Navtel Communications and F5 Networks. The simulation generated 1,000 SIP calls per second; the test stopped when the testing equipment--not the network--reached its limits.

For more information about the CommuniGate SIP farm:
- read this article in VON Magazine