Page 664 of 906 NT8D15 E&M Trunk card553-3001-211 Standard 3.00 August 2005ApplicationsThe optional applications, features and signaling arrangements for each trunkare assigned through unique route and trunk data blocks. Refer to theFeatures and Services (553-3001-306) for information about assigningfeatures and services to trunks.PAD switchingThe transmission properties of each trunk are characterized byclass-of-service (COS) assignments in the trunk data block (LD 14). Theassignment may be non-Via Net Loss (non-VNL) or via Net Loss (VNL). Toensure stability and minimize echo when connecting to long-haul VNL (Tie)trunks, non-VNL trunks are assigned either Transmission Compensated(TRC) or Non-Transmission Compensated (NTC) class-of-service.The TRC and NTC COS options determine the operation of the switchablepads contained in the trunk circuits. They are assigned as follows:• TRC for a two-wire non-VNL trunk facility with a loss of greater than2 dB or for which impedance compensation is provided, or for afour-wire non-VNL facility.• NTC for a two-wire non-VNL trunk facility with a loss of less than 2 dBor when impedance compensation is not provided.
