Identifies the switching machine that provides Automatic Message Accounting (AMA) recording for terminating service.
NOTE 1: The first three characters identify the NPA (numeric plan area) number.
NOTE 2: The last three characters are either the central office unit number or the toll tandem screening office number.
NOTE 3: The central office unit and the toll tandem screening office subfields are mutually exclusive.
USAGE: This field is optional.
DATA CHARACTERISTICS: 7 numeric characters (including 1 preprinted hyphen)
EXAMPLE: 2 0 1 - P C R