
Watching ISDN Ports and Channels
•Fourth level: Channels available on a port
Each PRI port has one ISDN D channel. Each PRI port also has 23 ISDN channels (North America, Japan) or 30 ISDN B channels (Europe, Australia). The digital modem port has as many channels as there are digital modems configured on the board.
Watching ISDN Ports and ChannelsThe ISDN D channel is generally used to transmit signalling frames, such as call in progress, incoming call, or call accepted. Watching this channel provides diagnostic information about the ISDN connection phase. For example, if a RAS connection fails (during either
ISDN B channels transmit data frames after an ISDN connection is established. The first few data frames exchanged between local and remote sites correspond to a second connection phase to allow the establishment of the upper layer (for example, the PPP protocol).
NOTE
Before establishing a call, you cannot know which ISDN B channel will be used. Therefore, to be sure to capture call data, you must activate traces for all the ISDN channels.
To activate watching on one channel, select that channel in the configuration panel of the SynWatch dialog box. To activate watching on all of a port’s channels, select the port in the configuration panel. Use the left or right mouse button as follows to start or change watch activity:
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