A. Reference Conditions. The transmission objectives set forth in these regulations are based upon the use of standard telephone sets connected to a 48-volt dial central office and measured at a frequency of 1000 hertz. This does not preclude future designs based on new instruments or voltages other than 48 volts, provided that equivalent or better transmission is obtained.
B. Loop Resistance. A subscriber line shall have a loop resistance not exceeding the operating design of the associated central office equipment. Amplifiers and long line adaptors may be used to extend the central office equipment design limits; however, the objectives of these regulations shall be met.
C. Permissible Loss on Subscriber Loops. The maximum transmission loss objective of any one subscriber loop shall be 11 db. Subscribers' loops with losses in excess of 15 dB shall be considered as trouble requiring correction. The maximum transmission loss objective between any two subscribers on separate lines in the same central office shall be 22 db.
D. Permissible Loss on Local Interoffice Trunks. The maximum overall transmission loss objective, including the loss in terminating equipment on local interoffice trunks, shall be 7 db. Local interoffice trunks with losses in excess of 11 db shall be considered as troubles requiring correction.
E. Permissible Loss on Toll Trunks. The maximum overall transmission loss objective, including the loss in terminating equipment for toll connecting trunks, shall be 4 db. Toll connecting trunks with losses in excess of 8 db shall be considered as troubles requiring correction. The maximum loss in intertoll trunks shall be consistent with the requirements of a nationwide switching plan.
F. Permissible Noise on Subscribers' Lines. Subscribers' lines with noise in excess of 40 db above reference level shall require correction. "Reference level" is defined as 90 db (referred to as one milliwatt).