AudioCodes Mediant 3000, User Manual

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User's Manual 176 Document #: LTRT-89729
Mediant 3000
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).
Notes:
•
For T.38 Version 3 support, ensure that the relevant DSP firmware
template is installed on the device. For a list of supported DSP
templates, see DSP Templates on page
859 .
•
The CNG detector is disabled in all the subsequent examples. To disable
the CNG detector, set the 'CNG Detector Mode' parameter
(CNGDetectorMode) to
Disable .
13.2.3.1 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).
13.2.3.2 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.