Methods and systems for identifying calls connected without answer supervision and for automatically generating billing information for these calls are disclosed. A monitoring device copies signaling messages associated with calls. The signaling messages are correlated into call detail records. The call detail records are analyzed to identify calls connected without answer supervision. In one implementation, calls that exceed a predetermined duration and for which no answer message was returned from the terminating end office are identified as calls without answer supervision. For these calls, billing records may be generated and forwarded to a network billing center.