How many calls will Asterisk handle?We see this question a lot and have quite a bit of experience with Asterisk and high loads. We also see a lot of answers with incomplete or inaccurate information. To help clear any confusion, we decided to post the information that we have learned.MORE...
About the Free VoIP Quality TestThis free VoIP quality test is designed to help you evaluate how well your network will handle VoIP service. Most problems related to VoIP service are due to inadequate bandwidth or poor network conditions provided by the Internet Service Provider (ISP). This VoIP test should give you an idea of the VoIP quality you can expect on your VoIP Calls.
VoIP Firewall TestThis VoIP firewall test will check some of the UDP ports used for VoIP service. The UDP ports required for service to work may vary among providers but are generally as follows:
-   5060-5160       SIP (for signaling)
-   10000-20000   RTP (for voice)
-   4000-4999       T.38 (for Fax)
While the firewall test does not check all the ports, this test should give you some indication of problems related to firewall.
VoIP Speed TestThis VoIP Speed test will check the speed and the consistency of the speed on your network. Typically the upload speed is what creates issues. As a general rule you can count on 80k of bandwidth for each call using the typical G711 CODEC. Other CODECs can use as little as 20k or as much as 240k. If you are unsure, check with your provider.
You should also note that the speed test will tell you how much bandwidth you have, but you need to have a bandwidth managing router like the Cisco RVS4000 to ensure the bandwidth required for VoIP calling is always available. Otherwise, high activity on computers could create serious problems with VoIP call quality.
VoIP SIP TestThis VoIP test will check for jitter and packet loss by simulating 10 simultaneous calls. Most VoIP hardware is designed to deal with a certain amount of jitter and can reconstruct lost packets. Excessive jitter will create VoIP echo problems. Excessive packet loss will cause distorted VoIP calls.