There's 10 simultaneous calls allowed, but in actuality, 20 is allowed since it can overflow to the resilient controller. It is also setup with 10 simultaneous calls.
These are the tests I did to try and simulate a network congestion alarm: Remember: These tests are on IP/XNET trunks.
1) Changed bandwidth setting under network topology to 1Kb. I got a busy tone on both incoming/outgoing calls.
2) Chanaged bandwidth back to normal. Changed the number of simultaneous calls to 1 under ICP/PBX under ICP/PBX Networking. I was able to make many simultaneous incoming/outgoing calls.
In both tests, the system did not generate a network congestion alarm. It leads me to believe that this alarm only applies to TDM trunks and not IP/XNET trunks.