AudioCodes Media 800 MSBR

User's Manual 162 Document #: LTRT-12809
Mediant 800 MSBR
To configure whether to pass V.34 over T38 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 T38 Version' parameter (SIPT38Version) in the Advanced
Parameters page (Configuration tab > VoIP menu > SIP Definitions > Advanced
Parameters) to configure one of the following:

Pass V.34 over T.38 fax relay using bit rates of up to 33,600 bps ('SIP T38 Version' is
set to Version 3).

Use Fax-over-T.38 fallback to T.30, using up to 14,400 bps ('SIP T38 Version' is set to
Version 0).
Note: The CNG detector is disabled in all the subsequent examples. To disable the
CNG detector, set the 'CNG Detector Mode' parameter (CNGDetectorMode)
to Disable.
16.2.3.1 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. In 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. In the Fax/Modem/CID Settings page, do the following:
a. Set the 'Fax Transport Mode' parameter to 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).
e. Set the 'V.34 Modem Transport Type' parameter to Enable Bypass
(V34ModemTransportType = 2).
2. Set the ini file parameter, V34FaxTransportType to 2 (Bypass).
16.2.3.2 Relay Mode for T.30 and V.34 Faxes
In this scenario, V.34 fax machines are forced to use their backward compatibility with T.30
faxes and operate in the slower T.30 mode.