Telephone line connection, Handset connection – CTI Products NCB/IM with Internal PSTN Modem User Manual
Page 18
CTI Products, Inc.
NCB/IM User Guide
2. Setup and Operation
12
Telephone Line Connection
The telephone circuit connection must be made using
the “LINE” connector
Dial-Up
A dial-up connection uses a 2-wire connection scheme to a standard telephone circuit. A standard telephone
cord can be used.
Leased-Line
A leased-line connection can use either a 2-wire or 4-wire scheme to a dedicated leased-line circuit:
2-Wire Leased-Line
In 2-wire Leased-Line mode, the audio circuit must pass audio simultaneously in both directions. For this
mode, use pins 3 & 4 (red and green) of the “LINE” connector (see “A
”). Pins
2 and 5 are unused in 2-wire mode.
For testing “on the bench” in 2-wire Leased-Line mode, two NCB units may be connected “back-to-back” using
the standard modular telephone cable provided with each NCB unit. For this short cable back-to-back
connection, however, the OPTION A Switch 7 must be placed in the DOWN position (followed by resetting
the NCB unit) on BOTH NCB units. This lowers the transmit level to prevent clipping of the signal due to the
short (near lossless) cable. Be sure to return OPTION A Switch 7 to the UP position before installing the NCB
unit in the field.
4-Wire Leased-Line
In 4-wire Leased-Line mode, two pairs are used, one for Transmitting to the other
NCB and one for Receiving from the other NCB. For this mode, pins 3 & 4 (red
and green) of the “LINE” connector carries ‘transmit audio’ from this unit to the
other unit and pins 2 & 5 (black and yellow) carries ‘receive audio’ to this unit
from the other unit. A 4-wire leased-line telephone circuit has two channels and
each channel carries audio in only one direction.
For testing “on the bench” in 4-wire Leased-Line mode, two NCB units must be connected “back-to-back” by
connecting the transmit pair of each unit to the receive pair of the opposite unit. This cannot be done with the
telephone cable having modular connectors on both ends, as this cable is wired “straight through”. Instead, use
the modular plug to spade lug cables provided. Also, for this short cable back-to-back connection, the
OPTION A Switch 7 must be placed in the DOWN position (followed by resetting the NCB unit) on BOTH
NCB units. This lowers the transmit level to prevent clipping of the signal due to the short (near lossless) cable.
Be sure to return OPTION A Switch 7 to the UP position before installing the NCB unit in the field.
Handset Connection
A
standard telephone handset or other audio input and output device may be
connected to the "AUDIO" connector to allow use of the simultaneous voice/data
feature of the NCB module. Audio directly from the telephone circuit is routed to
this connector during modem dialing and training to permit monitoring of call
establishment (as typical modems provide via an internal speaker). After training is
completed (when the CD LED turns on), bidirectional audio from the simultaneous voice/data system is
available at this connector. The audio on this connector is digitized and transferred across the modem link by
LINE
See A
for 4-Wire
Leased-Line
pinouts and wire
colors.
AUDIO
See A
for connector
type and pinout.