ZyXEL Communications ACCESSING INTERNET & INTRANET omni series - Manual (Page 73)

V.120 ISDN Communications 61
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]
The answering TA 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 them by using the following
commands:
ATS100=0 MLP channel bundling
ATS100=1 CCB channel bundling
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)