ADTRAN ISU 128 User Manual download pdf (Page 69)

Chapter 7. Protocol Options

54 ISU 128 User Manual 61202.029L2-1

FALLBACK

The FALLBACK asynchronous rate adaption protocol provides the capability

to automatically establish calls with other ISDN terminal adapters, Switched

56 DSUs, V.34 modems (optional), as well as other ISUs using a single config-

uration. To communicate with analog modems, the ISU 128 with V.34 modem

option (part numbers 1202029L3) must be used.

The ISU 128 must be optioned as follows for FALLBACK operation:

• Any asynchronous bit rate up to 115.2 kbps which is supported by the

DTE.

• Flow control must be enabled and supported by the DTE.

FALLBACK supports the following protocols based on the call type: BOND-

ING Mode 1, V.120, T-Link, and V.34.

When answering calls, the ISU 128 uses the incoming call type to determine

which rate adaption protocols to support. See Table 7-A for the call type and

the supported rate adaption protocols.

Table 7-A

Rate Adaption Protocols

Call Type

Rate Adaption

Protocols Supported

Typical Units Supported

Data 64k BONDING Mode 1 ISUs

V.120 ISDN TAs

PPP PPP compatible bridges/routers

Data 56k V.120 ISDN TAs

T-Link 2-Wire Switched-56 DSUs

PPP PPP compatible bridges/routers

Speech or Audio V.34 V.34 compatible modems

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ADTRAN ISU 128 User Manual Page 69