Filter
Top Products
Chapter 1. Understanding ISDN and the ISU 128
2
ISU 128 User Manual 61202.029L2-1
over ISDN. The ISU 128 may be viewed as an
ISDN dial modem
that allows
cost-effective high-speed data transmission at rates up to 128 kbps.
The ISU 128 has one RJ-45 jack available on the rear panel for network connec-
tion (see Figure 1-1). The RJ-45 jack labelled
ISDN IFC
is for ISDN Basic Rate.
ISDN Basic Rate service divides a standard telephone line into three digital
channels capable of simultaneous voice and data transmission. The three
channels are comprised of two bearer (B) channels at 64 kbps and one data (D)
channel at 16 kbps (2B+D).
The ISU 128 also supports a leased digital connection that allows data to be
transferred at up to 128 kbps over a 2-wire facility using the U-interface jack
labelled
ISDN IFC
. This type of service is a permanent connection between
end points and is sometimes referred to as a leased connection, a dedicated
connection, a nailed-up connection, a private circuit, or a limited distance mo-
dem connection. These types of service are referred to in this manual as
Leased Line Service.
Figure 1-1
ISU 128 Rear Panel
Dialing from the ISU 128 is accomplished in a variety of ways:
• From the front panel
• From up to ten stored numbers
• Through an RS-366 dial port used in facsimile and video conferencing ap-
plications
• Over the DTE interface using the AT command set
• With V.25 bis in-band dialing (used in applications such as LAN/WAN
bridging)