H3C Technologies H3C MSR 50 - Manual (Page 854)

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Table 304 Configuration items
Item Description
Fax Protocol
Specify the protocol used for fax communication with other devices.
• T.38—Use T.38 fax protocol. With this protocol, a fax connection can be set up
quickly.
• Standard T.38— Use the standard T38 protocol of H323 or SIP. The fax negotiation
mode depends on the protocol used (H323 or SIP).
Configure the fax pass-through mode.
• G.711 A-law.
• G.711 μ-law.
The pass-through mode is subject to such factors as packet loss, jitter and delay, so the
clocks on both communication sides must be kept synchronized. Only G.711 A-law
and G.711 μ−law are supported, and the VAD function should be disabled.
ECM Fax
As defined in ITU-T, the error correction mode (ECM) is required by the half-duplex and
half-modulation system running ITU-T V.34 protocol for fax message transmission.
Besides, the G3 fax terminals working in full duplex mode are required to support
half-duplex mode, namely, ECM.
The fax machines using ECM can correct errors, provide the automatic repeat request
(ARQ) function, and transmit fax packets in the format of HDLC frames. On the
contrary, the fax machines using non-ECM cannot correct errors and they transmit fax
packets in the format of binary strings.
• Enable—Enable ECM for fax.
• Disable—Disable ECM for fax.
By default, ECM fax is disabled.
ECM can work only if fax machines on both sides support ECM and the gateway is
configured with ECM.
You must enable ECM mode for the local numbers and call routes corresponding to the
fax sender and receiver in the ECM mode.
CNG Fax Switchover
Function
CNG fax switchover is used to implement the fax mailbox service through
communication with the VCX. When the local fax machine A originates a fax call to the
peer fax machine B, if B is busy or is unattended, A can send fax call to the fax mailbox
of the VCX. With CNG fax switchover enabled, the voice gateway can switch to the fax
mode once it receives a CNG from A.
• Enable.
• Disable.
The function is disabled by default.
Codec Type and
Switching mode for
SIP Modem
Pass-through
Configure the codec type and switching mode for SIP Modem pass-through function.
• Standard G.711 A-law—Adopt the G.711 A-law codec type and Re-Invite switching
mode.
• Standard G.711 μ-law—Adopt the G.711 μ-law codec type and Re-Invite switching
mode.
• NTE Compatible G.711 A-law—Adopt the G.711 A-law codec type and
NTE-compatible switching mode.
• NTE Compatible G.711 μ-law—Adopt the G.711 μ-law codec type and
NTE-compatible switching mode.