Version 6.2 449 February 2011
SIP User's Manual 8. IP Telephony Capabilities
• EnableSilenceCompression
• EnableEchoCanceller
Note: This mode can be used for fax, but is not recommended for modem
transmission. Instead, use the modes Bypass (see ''Fax/Modem Bypass
Mode'' on page 446) or Transparent with Events (see ''Fax / Modem
Transparent with Events Mode'' on page 448) for modem.
8.3.7.2.8 RFC 2833 ANS Report upon Fax/Modem Detection
The device (terminator gateway) sends RFC 2833 ANS/ANSam events upon detection of
fax and/or modem answer tones (i.e., CED tone). This causes the originator to switch to
fax/modem. This parameter is applicable only when the fax or modem transport type is set
to bypass, Transparent-with-Events, V.152 VBD, or G.711 transport. When the device is
located on the originator side, it ignores these RFC 2833 events
Relevant parameters:
IsFaxUsed = 0 or 3
FaxTransportType = 2
FaxModemNTEMode = 1
VxxModemTransportType = 2
8.3.7.3 V.34 Fax Support
V.34 fax machines can transmit data over IP to the remote side using various methods.
The device supports the following modes for transporting V.34 fax data over IP:
Bypass mechanism for V.34 fax transmission (see ''Bypass Mechanism for V.34 Fax
Transmission'' on page 449)
T38 Version
0 relay mode, i.e., fallback to T.38 (see ''Relay Mode for T.30 and V.34
Faxes'' on page 450)
Usi
ng the ini file parameter V34FaxTransportType, you can configure whether to pass V.34
over T38 fax relay, or use Bypass over the High Bit Rate coder (e.g. PCM A-Law).
Note: The CNG detector is disabled (CNGDetectorMode = 0) in all the subsequent
examples.
8.3.7.3.1 Bypass Mechanism for V.34 Fax Transmission
In this proprietary scenario, the device uses bypass (or NSE) mode to transmit V.34 faxes,
enabling the full utilization of its speed.
Configure the following parameters to use bypass mode for both T.30 and V.34 faxes:
FaxTransportMode = 2 (Bypass)
V34FaxTransportType = 2 (Bypass)
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