Reports for Monitoring › Interpreting Data in Reports › Call Legs and Bi-Directional Data

Call Legs and Bi-Directional Data

A VoIP call consists of two call legs when it is first placed:

• Origination party. Call setup metrics apply to this leg.
• Destination party. Call setup metrics do not apply to this leg of the call.

But as the call travels across the network, the call legs are considered directional. The origination party is not always the sender of call data. Often during the call, the origination party receives call data from the destination party.

UC Monitor captures these metrics and uses them in calculating and reporting on call performance. For Cisco deployments, it gathers call setup data from call server flows. The product also bases delay measurements on the timing of flows between the originator and the call server. UC Monitor derives the delay-to-dial tone and post-dial delay call setup metrics from these timings.

The collector monitors call legs in each direction, without eavesdropping on the calls. The collector also obtains call performance data from call legs that involve endpoints in the PSTN. For PSTN-related data, the collector polls the Cisco voice gateway that routed them, or passively receives call quality reports from Avaya gateways. The collector can gather data from all call legs that are processed by the call servers with which it shares a switch.

UC Monitor reports use the data from each call leg to evaluate the listening quality that users experienced. For example, in Call Watch reports, listener call quality is expressed as MOS from call legs traveling toward each Location.

Reports do not show quality statistics for call legs that terminate at a voice mail server or other device where these statistics are not available. For example, Cisco Unity and Unity Express do not report call quality statistics. For calls that are forwarded or transferred, reports show the IP address or directory number of the final destination, not the originally dialed destination.