We're accepting CDR data for a customer from several vendors' solutions. Cisco is one of them. The problem is we are working in sort of a vacuum. The customer recently switched all their 5 digit extensions to 10 digits. Assuming we have very limited knowledge of the partitioning and details of the network setup for Cisco, how do we deal with the CDR?
Specifically, how do we reliably tell incoming calls from outgoing and internal calls? It was pretty painless in the past when the extension digits were shorter. Dialed digits were easily determined just by comparing lengths. Now however, short of knowing every possible extension ahead of time (they are actually combining CDR from dozens of sites into one FTP feed to us), it has become practically impossible to process the calls.
Given the limitations of our knowledge of the Cisco setup, is there a reliable way to determine the type of call in the raw CDR file?