ART does not do any reporting on the failed calls.
The number of failed calls for a particular user can be got by querying the CDR database for "callingpartynumber"(same as the user's DN) and "destination cause value"(as any of the call failure cause codes).
As some of the failed call CDRs are of zero duration, the CdrLogCallsWithZeroDuration Flag has to be enabled in the CallManager.
