ZyXEL Communications omni.net D, Technical Reference

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Technical Reference for ZyXEL omni.net series
8-10
Dialing Pre-stored Phone Numbers
The 40 phone numbers stored in the NVRAM can also be used to place a bundled call with V.120 or X.75, by
using the [ATDSn] command:
ATDSn
n=0-39 Dial the (n)th phone number twice for both bundle connections.
ATDSn+ n=0-38 Dial the (n)th phone number for the first connection and dial the (n+1)th phone
number for the second connection.
n=0-39
m=0-39
Dial the (n)th phone number for the first connection and the (m)th phone number for
the second connection. ATDSn+Sm
For example,
S1<Enter>
will dial the number stored in location ‘1’, and the number
stored in location ‘2’ for the bundle connection.
Table 51. AT Command for Dialing Pre-stored Phone Numbers
Using V.42bis Data Compression
The following AT commands are used to switch the V.42bis data compression on or off for ISDN
data calls when using X.75 or V.120 protocols:
V.42bis AT Command Description
AT&K44
Enable V.42bis on V.120 and X.75 ISDN call.
AT&K00 Disable V.42bis on V.120 and X.75 ISDN call.
Table 52. V.42bis AT Command
Bundle Connection with V.42bis Data Compression
If both sites have set [AT&K44] to enable V.42bis negotiation then XID frames will be exchanged
through the main B-channel which corresponds to the call established by the first SETUP message.
Only one data compression channel will be used in bundle connections. That means the
compression is done before packet disassembly and the decompression is done after packet
assembly.
The compression ratio of V.42bis is commonly recognized as up to 4:1 for text files. If the line
speed is 128Kbps, then the DTE speed may reach 512Kbps. This makes the DTE's normal RS-232