Zhone Technologies IMACS Network Device - Manual (Page 44)

Zhone Technologies, Inc. IMACS Product Book, Version 4
March 2001 Page 40
Voice Channel Bank Application
This is the simplest IMACS application, which can be used by a service provider. The IMACS is used in this
configuration when one or more digital T1/E1 trunks are needed to interface with analog PBXs or key systems at the
customer premises. In the US, the break-even point for bringing in a T1 trunk as opposed to multiple analog lines is
typically 6 analog lines. As a result, there is a huge market for cost-effective voice channel bank such as the IMACS.
A single IMACS can be used to provision up to 62 analog POTS lines (FXS, FXO, E&M) on digital Central Office
switches as shown in Figure 11.
Figure 11—IMACS As A Voice Channel Bank
POTS/
CLASS
D
S
X
P
A
N
E
L
Local Digital Switch
Customer Premise
Central Office
Max 8 T1/E1
IMACS
• 62 POTS/CLASS Lines
The IMACS can also be deployed in applications, which do just the reverse of voice channel banks. This is most
likely to be found in wireless local loop applications in which the wireless service provider may use a state-of-the-
art wireless local loop. The output of the wireless base station is normally a T1/E1. However, the existing PSTN
may still have analog switches. The IMACS is used to convert from robbed-bit signaling/CAS to analog trunks
(FXO).
The voice channel bank platform can be upgraded to provide an array of additional services just by adding
application modules to the chassis. It comes with a built-in suite of testing and diagnostics tools, which significantly
enhance the service and support capabilities.
TR-008 Application
BellCore’s TR-008 standard describes the requirements necessary for a Local Digital Switch (LDS) to connect to a
remote terminal (RT) across a T1 (1.544Mbps) digital interface. The standard allows supporting from one to four
T1s per RT without facility Automatic Protection Switching (APS), and two to five T1s with facility APS.
The LDS can interface the RT in Mode I (no concentration), Mode II (2:1 concentration), and Mode III (24 special-
service circuits on 24 DS1 time-slots). TR-008 supports traditional POTS, CLASS, and Coin services but does not
support ISDN BRI. If the service provider deploys a channel bank at the customer premise that does not provide
TR-008 capability then it needs a 1/0 DCS with TR-008 capability at the central office to integrate with the LDS.
The IMACS also supports TR-008 switch integration. The IMACS with TR-008 operation can connect directly to
the LDS, eliminating the need for the 1/0 DCS as shown in Figure 12a.