You can manage only what you can measure. Managing a VoIP network requires some rigorous data collection and special analysis techniques.In addition to measuring latency, jitter and hop counts, it’s essential to calculate an overall voice quality score such as a Mean Opinion Score or R-factor score. 

VoIP monitoring tools calculate such scores by using a formula known as the E-Model. This is calculated based on statistics collected from the network and then taking into consideration factors such as codec compression, jitter, delay, packet loss and hop count. These factors all effect the user’s perception of call quality.

Since you have to take into account many different variables from networking side as well as traditional telecom industry, individually, such tools are not well suited for VoIP management and you need specialized VoIP tools such as the ones available from Agilent Technologies, Brix Networks, Empririx, Radcom and Qovia. These tools not only use MOS technology but also let you systematically gather data and in most cases relate to other network events and statistic to help diagnose problems and create SLA (service level agreement) reports.