A multifunctional analog TRK circuit board is designed so as to serve as both
loop,
ground start, DID, E&M, ring down and both way TRK. Thus, the various analog TRK
circuits are embodied in a single TRK board, thereby increasing productivity compared
to the conventional system requiring separate TRK circuit boards. The multifunctional
TRK circuit is selectively controlled to provide desired TRK functions.
