This read-write integer serves as a correlation key linking together related call/connection detail records (CDRs) - specifically start and end records along with their associated cell/frame counts - for a given connection session. Admins or billing/reporting systems use this key to reassemble a complete usage record for a connection from its separate start, end, and count entries. For example, a billing system matching a connection's start record to its corresponding end record and traffic counts would use ausmCDRNumber as the join key across those separate log entries.