Using “D” Messages for Layer 3
• 8-14 •
The H.110 Basic Rate ISDN Board
indicating that dial tone was present. The Keypad messages are the digits
as they dialed. These are sent by the terminal as INFOrmation messages
with a Keypad element. When enough digits have been dialed to complete
the call, an ALERTing message is sent with the progress indicator for
inband tones and the signal indicating ringback. A CONNect follows when
the call is answered. A “DD” command is issued with a cause of normal
clearing to end the call. The terminal responds with a RELease message.
This causes the board to send a RELease COMplete message to end the
call.
8.8 TE Call Handling Examples
Call handling from the perspective of the TE side is similar to that for an
NT. However, there are some differences in which messages are sent and
which information elements are present.
8.8.1 Originating a Call
In this example, the board is originating a call. As the board is a piece of
automatic equipment, it is assumed that the “enbloc” sending method is
always used for originating calls.
commands
responses
description
DS10S5551000
SETUP message
DP10NF
CALL PROCeeding message
DA10IR
ALERTing message
DC10NF01
CONNect message
DD1010N
DISConnect message
DR100F
RELease COMplete message
The SETUP command indicates that the call is a speech call to 5551000.
There are no progress indicator or signal elements. The network responds
with a CALL PROCeeding message with no progress indicator and a tones
off signal. This means that the network has accepted the call and is passing
it on. When the terminal at the far end has accepted the call and is alerting