Supporting V.34 Faxes; Using Bypass Mechanism For V.34 Fax Transmission; Using Relay Mode For Both T.30 And V.34 Faxes - 3Com V7111 - VCX 4 Channels Analog FXO Media Gateway User Manual

Supporting V.34 Faxes

V.34 faxes do not comply with the T.38 relay standard. 3Com therefore provides the optional
modes described in

"Using Bypass Mechanism for V.34 Fax Transmission

Relay Mode for Both T.30 and V.34
Note that the CNG detector is disabled (CNGDetectorMode=0) in all the following examples.
Using Bypass Mechanism for V.34 Fax Transmission
In this proprietary scenario, the Gateway uses a high bit-rate coder to transmit V.34 faxes,
enabling the full utilization of its speed.
Use the following configurations as a guide:
FaxTransportMode = 2 (Bypass)
V34ModemTransportType = 2 (Modem bypass)
V32ModemTransportType = 2
V23ModemTransportType = 2
V22ModemTransportType = 2
V21ModemTransportType = 2
In this configuration, both T.30 and V.34 faxes work in Bypass mode.
Or
FaxTransportMode = 1 (Relay)
V34ModemTransportType = 2 (Modem bypass)
V32ModemTransportType = 2
V23ModemTransportType = 2
V22ModemTransportType = 2
V21ModemTransportType = 2
In this configuration, T.30 fax uses T.38 Relay mode while V.34 fax uses Bypass mode.

Using Relay Mode for Both T.30 and V.34 Faxes

In this scenario, V.34 fax machines are compelled to use their backward compatibility with
T.30 faxes; as a T.30 machine, the V.34 fax can use T.38 Relay mode.
Use the following configuration as a guide:
FaxTransportMode = 1 (Relay)
V34ModemTransportType = 0 (Transparent)
V32ModemTransportType = 0
V23ModemTransportType = 0
V22ModemTransportType = 0
V21ModemTransportType = 0
Both T.30 and V.34 faxes use T.38 Relay mode. This configuration forces the V.34 fax
machine to operate in the slower T.30 mode.
3Com VCX V7111 VoIP SIP Gateways User Manual
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