VoIPmonitor is open source live network packet sniffer and call recorder for linux or posix unix which analyzes SIP and RTP protocol. It can run as daemon or analyzes already captured pcap files. For each detected VoIP call voipmonitor calculates statistics about loss, burstiness, latency and predicts MOS (Meaning Opinion Score) according to ITU-T G.107 E-model so operator centers can quickly decide which calls are bad. 