Samsung SMG-400 User Manual page 22

Chapter 2
2-4
System Boards
G.165 compliance, 16ms echo canceler
DTMF detection and generation function
U-Law/A-Law support
Input/Output Gain Control
VAD/CNG support
SLC Part
The SLC (Subscriber Line Circuit) part provides four analog telephone ports and allows
connection to a Private Branch Exchange (PBX), the loop start trunk port of a Key Telephone
System (KTS) or a connection to a general analog telephone through each port.
The features and functions of the SLC part are as follows.
It provides a current of -48VDC for the connected subscriber telephone.
It provides the Ring signal that indicates the subscriber telephone is ringing.
It reads the hook ON/OFF status, dial pulse, Ring trip, call answer status of the subscriber
telephone.
It protects the subscriber circuit and system from lightening or high voltages, AC voltage
crossing etc. that are generated from the subscriber line.
It converts the analog signal into a digital signal with the PCM method to send them to the
control module. It also converts the digital signal with the PCM method into an analog
signal.
It provides hybrid function to separate the sending path and receiving path from the analog
voice signal.