Controlling the B-Channels • 9-1 •
The H.110 Basic Rate ISDN Board
9.0 Controlling the B-Channels
This section describes the process used for controlling the B-channels on
the Infinity Series H.110 Basic Rate ISDN Board. The steps necessary for
configuring a board will be described. Basic functions such as making a
connection, playing call progress and DTMF tones, and detecting DTMF
tones and energy will be described. In addition, examples of making
incoming and outgoing calls combining several functions are included.
Control of the B-channels is completely independent of call control
procedures involving Layer 3 messages. Neither “LC” or “D” commands
affect the switching of the B-channels, and the commands described in this
section do not result in any Layer 3 Q.931 messages being sent.
9.1 Overview of the Command Structure
The command set described in this section are called the “C” Commands.
Each of these commands instructs the board to take all the actions
necessary to perform a function such as making a connection, playing a
tone, or detecting DTMF digits. Thus, the command to detect DTMF
digits will play dial tone to the B-channel, connect it to a DTMF detector,
and activate that detector.
Many of the commands use a common form for the various arguments.
The B-channel number is usually the first argument, and will be between
00 and 1F. Two B-channels are allocated to each port, with the B1
channels having even numbers and B2 channels having odd numbers.
Thus, B-channels 00 and 01 are the B1 and B2 channels for port 0, 02 and
03 are the B-channels for port 1, and so on through 3E and 3F which are
the B-channels for port 1F.
The arguments used to define the source or destination consist of a four
digit hexadecimal number. The first two digits are used to indicate the
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