AudioCodes Mediant 500L - Bypass Mechanism for V.34 Fax Transmission

Version 7.2 195 Mediant 500L Gateway & E-SBC
User's Manual 14. Media

Bypass mechanism for V.34 fax transmission (see ''Bypass Mechanism for V.34 Fax
Transmission'' on page
195)

T.38 Version 0 relay mode, i.e., fallback to T.38 (see ''Relay Mode for T.30 and V.34
Faxes'' on page
196)
To configure whether to pass V.34 over T.38 fax relay, or use Bypass over the High Bit
Rate coder (e.g. PCM A-Law), use the 'V.34 Fax Transport Type' parameter
(V34FaxTransportType).
You can use the 'SIP T.38 Version' parameter (SIPT38Version) to configure one of the
following:

Pass V.34 over T.38 fax relay using bit rates of up to 33,600 bps ('SIP T.38 Version' is
set to Version 3).

Use Fax-over-T.38 fallback to T.30, using up to 14,400 bps ('SIP T.38 Version' is set
to Version 0).
Note:
• Interworking of T.38 Version 3 is supported only for Gateway calls. For SBC calls,
the device forwards T.38 Version 3 transparently (as is) to the other leg (no
transcoding).
• The CNG detector is disabled in all the subsequent examples. To disable the CNG
detector, set the 'CNG Detector Mode' parameter (CNGDetectorMode) to Disable.
14.2.3.1 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.
 To use bypass mode for T.30 and V.34 faxes:
1. On the Fax/Modem/CID Settings page, do the following:
a. Set the 'Fax Transport Mode' parameter to Bypass (FaxTransportMode = 2).
b. Set the 'V.22 Modem Transport Type' parameter to Enable Bypass
(V22ModemTransportType = 2).
c. Set the 'V.23 Modem Transport Type' parameter to Enable Bypass
(V23ModemTransportType = 2).
d. Set the 'V.32 Modem Transport Type' parameter to Enable Bypass
(V32ModemTransportType = 2).
e. Set the 'V.34 Modem Transport Type' parameter to Enable Bypass
(V34ModemTransportType = 2).
2. Set the ini file parameter, V34FaxTransportType to 2 (Bypass).
 To use bypass mode for V.34 faxes, and T.38 for T.30 faxes:
1. On the Fax/Modem/CID Settings page, do the following:
a. Set the 'Fax Transport Mode' parameter to T.38 Relay (FaxTransportMode = 1).
b. Set the 'V.22 Modem Transport Type' parameter to Enable Bypass
(V22ModemTransportType = 2).
c. Set the 'V.23 Modem Transport Type' parameter to Enable Bypass
(V23ModemTransportType = 2).
d. Set the 'V.32 Modem Transport Type' parameter to Enable Bypass
(V32ModemTransportType = 2).