ADTRAN 1200063L1, Manual

Page: 20 / 137

Chapter 1. Introduction
1-4 DSU III TDM User Manual 61200063L1-20
2-Wire Switched 56 Backup Option
DATAPATH
®
is a Switched 56 service offered under various service
names by the local service provider. The services are generally provided
by the Northern Telecom DMS/SL100 family of central office switches.
DATAPATH allows the customer to pay for high speed data transfer, up
to 56 kbps, only when the unit is active. The dial up service is delivered
via a 2-wire local loop that can be up to 18,000 feet at a signal level of
-45dB.
V.32 bis Backup Option
The V.32 bis/42 bis modem in an asynchronous mode can use V.42 bis
data compression to make up for a slower connection rate. V.42 bis in-
creases the effective data throughput from 14.4 kbps to as high as 57.6
kbps, depending on the data type. No compression is supported in syn-
chronous operation.
Due to the limited bandwidth of the V.32 modem, employing this type of
service limits dial backup to only PORT 1. PORT 1 is backed up to a max-
imum of 14.4 kbps synchronous. For asynchronous operation, the backup
module may be configured to employ data compression so data rates
higher than 14.4 kbps may be supported.
1B+D Basic Rate ISDN Backup Option
ISDN service provides the customer with a switched 56/64 kbps circuit.
The default data rate for this option is 56 kbps. The 64 kbps data rate may
be accessed using the Smart Dial String as described in the chapter Config-
uring Dial Options on page 9-1. This option provides a U interface to the
ISDN network.