Services Units and Gateways
R2 Network Services Unit
R2 is a protocol converter that allows the R2 NSU to access an R2 National Public Switched
Telephone Network (PSTN) using MF-R2 digital trunk signaling. The 3300 ICP also receives
and processes Calling Line Identification (CLI) and allows the information to be displayed on
the user's telephone display screen. The R2 NSU supports two E1 links.
The R2 NSU supports the CCITT Blue Book, Volume VI, Fascicle VI.4, Specifications of
Signaling System R2, Recommendations Q.440 to Q.490 (with the exception of Echo
Suppression (Q.479), Test Calls (Q.490) and international signals).
The R2 NSU connects to a 3300 ICP Controller through a fiber optic cable. Additional digital
trunk capacity can be added to the 300 ICP by chaining two NSUs together. NSUs are chained
together by connecting a Category 5 crossover cable from a Copper Interface Module (CIM)
port on one NSU to a CIM port on the other.
The R2 NSU converts the following:
• Incoming MF-R2 signals from the PSTN into Digital Private Network Signaling System
(DPNSS) signals for the system
• Outgoing DPNSS signals from the system into MF-R2 signals for the PSTN.
The R2 NSU front panel consists of the following components:
• RS-232 serial port (DB-9 connector to a PC) for maintenance purposes such as field
installation, database upgrade, access to logs, and modem connection for remote access
• Ethernet port (RJ-45 connector) for future use
• Two FIM ports - 820nm multimode only (1 Tx, 1 Rx)
• Two CIM ports
• Faceplate LEDs
• Reset button.
Figure 22: R2 Network Services Unit Front Panel
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