Meridian Nortel 1 Option 11C Technical Reference Manual page 387

NT8D14 Universal Trunk Card Page 387 of 544
Paging operation
In the Paging mode, the Universal Trunk is connected to a customer-provided
paging amplifier system. When the trunk is accessed by dial-up or attendant
key operation, it provides a loop closure across control leads A and B. In a
typical application, this will transfer the input of the paging amplifier system
to the transmission path of the trunk.
Option 11C and 11C Mini Technical Reference Guide