This read-create enumerated value, used within the cpIwfExcessImpairment trap, identifies which type of CP-IWF port, pots(1), isdnBriB1(2), or isdnBriB2(3), experienced the excess-impairment event being reported. It tells an admin receiving the trap exactly which port class triggered the alert without needing to cross-reference separately. Seeing isdnBriB2(3) in a received trap tells the admin the impairment threshold was exceeded specifically on an ISDN B2 channel rather than a POTS port.