Using “D” Messages for Layer 3
• 8-15 •
The H.110 Basic Rate ISDN Board
the user, an ALERTing message is sent with a progress indicator of inband
tones and a ringback signal. The CONNect is sent after the far end
answers the call. When the far end disconnects the network sends a
DISConnect to the board with a cause of normal clearing and a signal of
tones off. This causes the board to send a RELease. The network then
responds with a RELease COMplete message to end the call. This has a
cause value of unspecified and a signal of tones off.
8.8.2
A Terminating Call
SETUP messages from the network always use “enbloc” sending to send
the called number. The SETUP message is broadcast with the group TEI.
It is up to the terminal to accept the call if the called number is part of its
programming.
commands
responses
description
DS10SNN5551000/5552000
SETUP message
DA10
ALERTing message
DC10
CONNect message
DC10A81
CONNect ACKnowledge
DD1010
DISConnect
DR10R
RELease
In this example, the SETUP message from the network indicates a speech
call with no progress indicator and no signal. The calling number is
5551000 and the called number is 5552000. The application sends a “DA”
command to cause an ALERTing message to be sent. There are no
arguments for the alerting message for a TE port. A CONNect follows
which causes the network to respond with a CONNect ACKnowledge.
The terminal sends a DISConnect message with normal clearing to hang up
on the call. The network responds with a RELease which causes the board
to send a RELease COMplete to end the call.