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User Manual - Configuration Guide (Volume 3)
Versatile Routing Platform
Chapter 2
IP Fax Configuration
2-2
IP telephone works after VoIP is configured. Generally speaking, faxes can now be
sent and received by using the default configuration of IP Fax only after a facsimile
machine is connected. The procedures of configuring IP Fax are mainly used to set up
the specific parameters of IP Fax or used for some specified conditions. For example,
fax operation can not be completed when the default gateway carrier transmit energy
level.
The task of IP Fax configuration is as follows:
z Check if configuring fax to use ECM mode
z Configure fax rate
z
Configure fax train mode
z Configure Fax Local-train Threshold Value
z Configure gateway carrier transmit energy level
z
Configure redundancy packet number of T38 fax protocol
z Configure the fax protocol intercommunicating with Cisco equipment
z Configure the intercommunication method with other equipment
All of the above configuration tasks should be carried out under the condition of dial
peer entity configuration mode.
2.2.2 Checking If Configuring Fax to Use ECM Mode
According to ITU-T Recommendation, Error Correction Mode (ECM) is necessary to
the transmission of facsimile message with the half-duplex and half-modulation system
of ITU-T V.34 protocol, at the same time the category G3# facsimile terminal operating
in full duplex mode is required to support half-duplex mode, that is to support ECM
mode.
If the facsimile adopts ECM mode, it has error correction function, and provides
automatic request for retransmission (ARQ) technology, at the same time facsimile
packet will be transmitted in the form of HDLC frame. On the contrary, if the facsimile
machine adopts non-ECM mode (the mode that facsimile must support), it has no error
correction function, and the facsimile uses binary string to transmit.
In actual configuration, if the facsimile machines on both sides support ECM mode, but
the configuration on the side of gateway is non-ECM mode, then non-ECM mode
should be adopted. If the facsimile machine on either or neither of sides does not
support ECM mode, then non-ECM mode should also be used. Only when the facsimile
machines on both sides support ECM mode and the gateway uses ECM mode, ECM
mode can be adopted.
Please perform the following configuration in dial peer configuration mode.
Table VC-2-1 Check if configuring fax to use ECM mode
Operation Command
Configuring fax does not use ECM mode fax-relay ecm disable
Configuring fax uses ECM mode no fax-relay ecm disable
The gateway does not use ECM mode by default.
2.2.3 Configuring Fax Rate
Subscribers can configure fax rate according to the different protocols.