Technical Reference for ZyXEL omni.net series

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.

ATDSn+Sm

n=0-39

Dial the (n)th phone number for the first connection and the (m)th phone number for

 

m=0-39

the second connection.

 

 

 

 

 

 

For example, ATDIS0+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

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