Applications - Nortel Circuit Card Installation Manual

Page 664 of 906

Applications

PAD switching
553-3001-211 Standard 3.00
NT8D15 E&M Trunk card
The optional applications, features and signaling arrangements for each trunk
are assigned through unique route and trunk data blocks. Refer to the
Features and Services (553-3001-306) for information about assigning
features and services to trunks.
The transmission properties of each trunk are characterized by
class-of-service (COS) assignments in the trunk data block (LD 14). The
assignment may be non-Via Net Loss (non-VNL) or via Net Loss (VNL). To
ensure 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 switchable
pads contained in the trunk circuits. They are assigned as follows:
• TRC for a two-wire non-VNL trunk facility with a loss of greater than
2 dB or for which impedance compensation is provided, or for a
four-wire non-VNL facility.
• NTC for a two-wire non-VNL trunk facility with a loss of less than 2 dB
or when impedance compensation is not provided.
August 2005