Nortel ISDN Signaling Link Description, Installation And Operation page 201

Figure 31
ITG Node Properties – DSP Profile Options tab
ITG Trunk 2.0 ISDN Signaling Link (ISL)
Install and configure ITG ISL Trunk node
4 Change the General and FAX option parameters, if required. To
revert to the default settings, click Reset Defaults.
The default DSP Profile Option settings for each codec are appropriate
for most applications. If you are not an expert in Voice over IP, do not
modify the Profile Options parameters. See "ITG Trunk DSP profile
settings" on page 135.
CAUTION
Description, Installation and Operation
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