User`s manual
MediaPack SIP User’s Manual 8. Telephony Capabilities
Version 4.6 177 June 2005
8.3.4 Supporting V.34 Faxes
V.34 faxes don’t comply with the T.38 relay standard. We therefore provide the optional modes
described under Sections
8.3.4.1 and 8.3.4.2:
Note that the CNG detector is disabled (CNGDetectorMode=0) in all the following examples.
8.3.4.1 Using Bypass Mechanism for V.34 Fax Transmission
In this proprietary scenario, the media gateway uses a high bit-rate coder to transmit V.34 faxes,
enabling the full utilization of its speed.
Refer to the following configurations:
FaxTransportMode = 2 (Bypass)
V34ModemTransportType = 2 (Modem bypass)
V32ModemTransportType = 2
V23ModemTransportType = 2
V22ModemTransportType = 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
In this configuration, T.30 fax uses T.38 Relay mode while V.34 fax uses Bypass mode.
8.3.4.2 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.
Refer to the following configuration:
FaxTransportMode = 1 (Relay)
V34ModemTransportType = 0 (Transparent)
V32ModemTransportType = 0
V23ModemTransportType = 0
V22ModemTransportType = 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.
8.4 Call Termination on MediaPack/FXO
The following six methods for call termination are supported by the MediaPack/FXO. Note that
the used disconnection methods must be supported by the CO or PBX.
• Detection of polarity reversal / current disconnect -
This is the recommended method. The call is immediately disconnected after polarity
reversal or current disconnect is detected on the Tel side (assuming the PBX / CO produces
this signal).
Relevant parameters: EnableReversalPolarity, EnableCurrentDisconnect,
CurrentDisconnectDuration, CurrentDisconnectDefaultThreshold and
TimeToSampleAnalogLineVoltage.