COMSPHERE 392xPlus Modems
1-2
November 1996
3920-A2-GN31-30
COMSPHERE 392x
Plus Models
The COMSPHERE 392xPlus modem is available in the following four models:
•
Model 3920Plus standalone singleport modem (model no. 3920-A1-41x).
•
Model 3920Plus standalone multiport modem (model no. 3920-A1-40x).
•
Model 3921Plus carrier-mounted
singleport modem (model no. 3921-B1-01x).
•
Model 3921Plus carrier-mounted
multiport modem (model no. 3921-B1-00x).
The last digit in the model number (x) varies, depending on whether the modem is equipped with
fixed Data Access Arrangement (DAA) or configurable DAA.
NOTE
Throughout this manual, reference to the 392x
Plus modem
represents all four models.
Model 3920
Plus Standalone Singleport Modem
The Model 3920Plus singleport is a standalone modem (Figure 1-1) capable of either
4-wire/2-wire leased-line or dial operation. This modem is controlled using either AT commands
or the DCP. The DCP consists of a liquid crystal display (LCD), three function keys, four
directional keys, and a row of 13 LED status indicators. For a better understanding of DCP
operation, refer to Chapter 3, DCP Operation.
Model 3920
Plus Standalone Multiport Modem
The Model 3920Plus multiport is a standalone modem (Figure 1-1), with an integral time division
multiplexer (TDM) and a modem sharing device (MSD) as standard equipment. The TDM
provides time division multiplexing of up to four independent ports over point-to-point lines using
the V.34 family or V.32 family modulation. The MSD allows multiple physical ports on a tributary
modem to share a single communication channel using the V.34 family, V.32 family, or TMp
modulation. The TDM/MSD multiplexer (commonly referred to as “mux” can be enabled or
disabled to allow a greater degree of application flexibility.
The 3920Plus multiport modem also operates over a 4-wire/2-wire leased or dial network and is
controlled using the same DCP employed on the Model 3920Plus singleport standalone modem.
