X.75 Outgoing Protocol; Synchronous Connections (For Omni.net Lcd/Lcd+M) - ZyXEL Communications omni.net LCD+M Technical Reference

X.75 Outgoing Protocol

The X.75 protocol can be chosen using the following AT commands:
AT Command
ATB00
X.75 with transparent layer 3.
ATB01 X.75 with T.70 NL.
The ATB0x commands not only specify the outgoing protocol, but also set the default layer 3 for an incoming
X.75 call without layer 3 information. It is important for both ends of an X.75 connection to execute the same
pre-assigned layer 3 protocol, as it reduces the chance that the ISDN TA will make the wrong protocol
selection.
For European ISDN (DSS1), the Low-Layer-Compatibility (LLC) information element in the SETUP message
can be used to specify the layer 3 protocol. Since this is an option for ISDN switches, some of the switches
might not deliver the LLC information element to the remote end.

Synchronous Connections (for omni.net LCD/LCD+M)

The ZyXEL omni.net LCD/LCD+M has synchronous mode included for transfering the data
synchronously. Use the following commands to choose the data rate for synchronous operation:
AT Command Data Rate
ATB11 64000bps
ATB19 56000bps
Table 47. AT Command for Synchronous Connections
There are two modes of synchronous operation:
Asynchronous commands, synchronous data (AT&M1): The omni.net LCD/LCD+M accepts
AT commands in asynchronous mode. Once the call is connected, it enters synchronous mode for
data transmission.
Synchronous mode (AT&M3*I1): The omni.net LCD/LCD+M accepts synchronous commands
from V.25 bis or a PC with an add-on synchronous card, and exchanges data synchronously with a
remote TA. (For more information on Async to Sync conversion, please refer to Chater 7.)
Technical Reference for ZyXEL omni.net series
Table 46. X.75 Outgoing Protocol
Description
8-5