Laptops should be able to do up to 50 calls before the laptop becomes the limiting factor in a call simulation. Desktops can usually go to 100 calls. Physical servers (non-virtual) should be able to go to 250 calls. 

Note: You do not want to use a Virtual Server for Call Simulations as they may have time slicing issues. Call Simulations are very sensitive to latency and jitter that can be caused by a Virtual Server.

Note that the destination should be a physical server to prevent the above limitations from affecting the call.

You will want to shut down other applications to prevent glitches caused by other software. Outlook for example, will check for messages every so often and will cause a hiccough that could show up as higher latency as well as jitter. Consider Antivirus Software to make sure it doesn’t run a scan during a test and make sure there are no backups going on. You will want to have 100% of the Server’s attention to Voice Simulation.

1 VoIP Call Simulation will product 1 phone call worth of traffic. If you increase the number of calls (over 10 calls) you can flood the network. You may want to consider an appropriate time of day when simulating a high number of phone call traffic.