Percent of Interstate. Usage (PIU) is defined as a factor to be applied to that portion of Non-Local Traffic comprised of interstate interMTA minutes of use in order to designate those minutes that should be rated as interstate access services minutes of use. The numerator includes all interstate interMTA minutes of use, less any interstate minutes of use for “Terminating Party Pays” services, such as 800 Services. The denominator includes all interMTA minutes of use less all minutes attributable to Terminating Party Pays services.