is there a open source software to observe the software and hardware performance of a server pbx AsteriskNow and even number of simultaneous call can support this server
I don’t know any open source tool at least not a popular one, you should benchmark your system and use Linux tools like top and monitor your system performance.
Hi,
If you want to test how many concurrent calls your server can handle you should use an opensource tool named SIPP.
I’ve just explained how it works to someone but in french 
Best Regards