1. A computer-implemented method comprising: (a) rating audio call quality by evaluating quality metrics for a set of calls against a defined set of threshold values; (b) determining site/time interval combinations for calls in the set of calls, wherein the determining comprises: (i) discretizing the calls into time intervals by identifying the time intervals in which the respective calls took place; and (ii) aggregating the discretized calls by site; and (c) evaluating a number of calls rated as poor within each site/time interval combination against a service level compliance requirement.