For those enterprise IT folks directly involved in network performance testing, Fluke Networks' NetTool Inline Network Tester has long been a staple.
The NetTool Inline Network Tester has just added VoIP-testing functionality. It works by connecting between the IP phone and network, and producing results in three key view screens:
The Boot Log documents key call events such as DHCP (Dynamic Host Configuration Protocol) address acquisition, DNS lookup of callservers and gateways, operating fil downloads and call server registration.
The VoIP Monitor screen shows measures transmitted frames, dropped frames, out-of-sequence frames, dropped packets and jitter;
The VoIP Log displays IP addresses, ports and codecs use.