Avaya Communication Manager Administrator's Manual page 1098

Screen Reference
Modem Mode
Valid entries
off
relay
pass-through
Redundancy
Valid entries
0 to 3
1098 Administrator Guide for Avaya Communication Manager
Usage
Turn off special modem handling when using this codec
set. In this case, the modem transmission is treated like
an ordinary voice call. This is the default for new
installations and upgrades to Communication Manager
R2.1.
With a codec set that uses G.711, this setting is required
to send modem calls to non-Avaya systems.
For users in regions using this codec, use relay mode for
modem transmissions over IP network facilities.
Note:
Modem over VoIP in relay mode is
Note:
currently available only for use by specific
analog telephones that serve as Secure
Telephone Units (STUs). Contact your
Avaya technical representative for more
information.
For users in regions using this codec, use pass-through
mode for modem transmissions over IP network facilities.
Usage
Enter the number of duplicate or redundant packets that
are sent in addition to the primary packet for all Modes
except pass-through and Clear-channel. The default is
0.