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Technical Reference for ZyXEL omni.net series
8-7
Making V.120 and X.75 Bundled Calls
Speeds of 128Kbps
BRI ISDN consists of three (2B+D) logical channels. Each B-channel can be used independently
for a dial-up connection running at 56Kbps or 64Kbps (Kbps = Kilo (1000) bits per second).
The two B-channels can be used together for a single data connection to provide 112K (with
In-Band Signaling) or 128K (when Out-of-Band Signaling is used). This is called a "Bundled
Connection".
Identifying your Line Provisioning
For bundled connections, the two B-channels of your ISDN line must be able to handle data circuit
switch connections with unrestricted 64K or 56Kbps line speeds. Two separate data calls will be
established consecutively.
NOTE: V.110 protocol does not support bundled call..
V.120 Bundled Call
A bundled V.120 connection is initiated at the calling site when [ATB20] (B-channel protocol V.120) has been
selected and the channel bundling mode has been enabled by an [AT&J3] command.
The channel bundling command [AT&J3] must be set on both the calling and receiving sides, otherwise a
single channel connection will be made.
AT Command Description
ATB20<Enter>
Set B-channel protocol to V.120.
AT&J3<Enter>
Enable the omni.net ISDN TA to make a bundled call.
AT&WZ<Enter>
If you want to save the setting.
Table 48. V.120 Bundled Call AT Command (1)
While 'ATJ&3' allows to make a bundle call in both call and answer modes, other bundled call settings are