H3C Technologies H3C MSR 50 - Manual (Page 848)

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Table 301 Configuration items
Item Description
Fax Protocol
Configure 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 H.323 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
Enable ECM fax. As defined in ITU-T, the 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, that is, ECM.
The fax machines using ECM can correct errors, provide the 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.
• Disable—Disable ECM.
By default, ECM is disabled.
To use ECM, fax machines on both sides and the gateway must support 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
Enable CNG fax switchover function. The 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 the 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 G.711 A-law as the codec type and use Re-Invite
switching for SIP Modem pass-through.
• 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.