Adtran ISU 128 User Manual

Chapter 7. Protocol Options

61202.029L2-1

ISU 128 User Manual

When originating calls to unknown units, the ISU begins protocol selection 
based on the local call type.  Data 64k is used for FALLBACK selected from 
Quick Setup

 menu.  Upon connection at 64k call type, BONDING, V.120, and 

PPP are attempted.  If connection is not made at 64k, the ISU 128 attempts an-
other call at 56k call type.  If connection is made at 56k, then V.120, T-Link, and 
PPP are attempted.  If connection is not made at 56k, then an audio call type is 
attempted, provided the ISU 128 with the V.34 modem option is used.  If the 
ISU connects the audio call type, the V.34 protocol is attempted for V.34 com-
patible modems.  Once a call connects, if the protocol cannot be negotiated, the 
protocol is negotiated as specified by S11 register (default is DSTOP). If this 
protocol fails, the call is disconnected.

If FALLBACK fails to determine which protocol is running, the user has the 
option to select which protocol will run. Figure 7-6 illustrates the FALLBACK 
default settings.

1=Netw. options

2=DTE options

4=Quick setup

5=Remote config

1=Clear Channel

2=BONDING mode 1

3=V.120

5=V.110

6=DSU 57.6 ASYNC

7=T-LINK

8=SAP

9=FALLBACK

0=PPP asyn-sync

1=Fallback Def.

1=Clear Channel

2=BONDING Mode 1

3=V.120

4=V.34

5=V.110

6=DSU 57.6 ASYNC

7=T-LINK

8=SAP

9=PPP asyn-sync