ASR are good indications, but if you break them down into further descriptive elements such as Call Completion ratios, Call abandon, do not answers, no route, etc… this will point you in other directions either internal to the switch (looping) or external interconnection.
We have a SS7/VOIP probe that not only generates SS7/VOIP based collelated CDRs but also Mou report, call disposition studies, OPC/DPC reports,etc….
for further information please email me at martyss7wiz@yahoo.com