Making A Bundled Call With V.120; Dialing Pre-Stored Phone Numbers - ZyXEL Communications Omni TA128 User Manual

Chapter 7 - V.120 ISDN Communications

Making a Bundled Call with V.120

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.
Type:
ATB20<Enter> (Set B channel protocol to V.120)
AT&J3<Enter> (Set the Omni TA128 to make a bundled call)
Type:
AT&WZ<Enter> (If you want to save the setting)
Once this is done, the ATD command will generate two consecutive SETUP messages to
invoke bundle initiation.
For the Northern Telecom switch, each BRI phone number can only be called once at
any given time. So if you dial this number, it will report "busy" to any other incoming
calls. In order to use two B channels for aggregation, we must place two calls with
different phone numbers. To do this, separate the two numbers with a "+" sign after the
"ATD" command:
ATDI[phone_number_1]+[phone_number_2]<Enter>
The answering Omni TA128 determines that the call is a bundle request: when AT&J3 is
set, and two consecutive SETUP messages are received. The two data calls are
established as one message. The phone company's ISDN line splits it off into two
messages. That is, the ISDN network treats them as two independent calls. Finally, the
receiving side receives one bundled message into the computer's serial port.
The success of a bundle connection initiation is indicated by the connect message
reported to the DTE:
CONNECT 115200/V120M 128K/LAPD
or
CONNECT 115200/V120M 128K/LAPD/V42b (with data compression)
If you are not using American ISDN, you can have a choice between Multiple Link
Protocol (MLP) or "cFos" channel bundling (CCB) two bundle protocols. You can set it
by the following commands:
ATS100=0
ATS100=1

Dialing pre-stored phone numbers

Use ATDSn, n=0,1,..,39, to dial the (n+1)th phone number twice for both the bundle
connections. Use ATDSn+Sm, (n and n=0,1,...,39) to dial the (n+1)th phone number for
the first connection and the (m+1)th phone number for the second connection.
For example, ATDIS0+S1<Enter> will dial the number stored in location '0' , and the
number stored in location '1' for the bundle connection.
MLP channel bundling
CCB channel bundling
7-3