AudioCodes Mediant 800B MSBR User Manual page 866

Parameter
Web/EMS: T.38 Max Datagram
Size
CLI: t38-mx-datagram-sz
[T38MaxDatagramSize]
Web/EMS: T38 Fax Max Buffer
CLI: t38-fax-mx-buff
[T38FaxMaxBufferSize]
Web: Detect Fax on Answer
Tone
EMS: Enables Detection of FAX
on Answer Tone
CLI: det-fax-on-ans-tone
[DetFaxOnAnswerTone]
Web: CED Transfer Mode
[CEDTransferMode]
Web: T.38 Fax Session
CLI: t38-sess-imm-strt
[T38FaxSessionImmediateStart
]
User's Manual
Defines the maximum size of a T.38 datagram that the device can
receive. This value is included in the outgoing SDP when T.38 is
used.
The valid range is 120 to 600. The default is 560.
Defines the maximum size (in bytes) of the device's T.38 buffer.
This value is included in the outgoing SDP when T.38 is used for
fax relay over IP.
The valid range is 500 to 3000. The default is 3000.
Determines when the device initiates a T.38 session for fax
transmission.

[0] Initiate T.38 on Preamble = (Default) The device to which
the called fax is connected initiates a T.38 session on
receiving HDLC Preamble signal from the fax.

[1] Initiate T.38 on CED = The device to which the called fax is
connected initiates a T.38 session on receiving a CED answer
tone from the fax. This option can only be used to relay fax
signals, as the device sends T.38 Re-INVITE on detection of
any fax/modem Answer tone (2100 Hz, amplitude modulated
2100 Hz, or 2100 Hz with phase reversals). The modem signal
fails when using T.38 for fax relay.
Note: This parameters is applicable only if the IsFaxUsed
parameter is set to 1 (T.38 Relay) or 3 (Fax Fallback).
Defines the method for sending fax/modem CED (answering)
tones.

[0] Fax Relay or VBD = (Default) The device transfers the
CED tone in Relay mode and starts the fax session
immediately.

[1] Voice Mode or VBD = The device transfers the CED tone in
either Voice or Bypass mode and starts the fax session on
V21 preamble.

[2] RFC 4733 Blocking RTP VBD = The device transfers the
CED tone in RFC 2833. This is applicable only to V.150.1
modem relay and fax bypass.

[3] RFC 4733 Along with RTP VBD = The device transfers the
CED tone in RFC 2833 and bypass, in parallel. For combined
V.150.1 modem relay and fax relay, use this option.
Enables fax transmission of T.38 "no-signal" packets to the
terminating fax machine.

[0] Disable (default)

[1] Immediate Start on Fax = Device activates T.38 fax relay
upon receipt of a re-INVITE with T.38 only in the SDP.

[2] Immediate Start on Fax & Voice = Device activates T.38
fax relay upon receipt of a re-INVITE with T.38 and audio
media in the SDP.
This parameter is used for transmission from fax machines
connected to the device and located inside a NAT. Generally, the
firewall blocks T.38 (and other) packets received from the WAN,
unless the device behind NAT sends at least one IP packet from
the LAN to the WAN through the firewall. If the firewall blocks
T.38 packets sent from the termination IP fax, the fax fails.
To overcome this, the device sends No-Op ("no-signal") packets
to open a pinhole in the NAT for the answering fax machine. The
866
Mediant 800B MSBR
Description
Document #: LTRT-12813