Reports the number of ISDN dial-in ports currently in use, counted without separating single-B from bonded 2B channels since bonded calls are already captured by the MP count, for this specific office direction — an outbound trunk grouping identified by an office-direction number from 0 to 255 (the table is indexed by that number). An admin polls this counter alongside its sibling userStatisticsOdn* objects to see how the mix of dial-up service types is distributed for this particular odn; it lets an admin see session-type counts broken down by which upstream office/trunk group the calls arrived through.