AudioCodes MSBG Series User Manual

User's Manual 1034 Document #: LTRT-27045
Mediant 1000B Gateway & E-SBC
Parameter Description

For the parameter to take effect, you must reset the device.
 When the device is configured to use V.152 to negotiate audio
and T.38 coders, the UDP port published in SDP for RTP and for
T38 must be different. Therefore, set the T38UseRTPPort
parameter to 0.
T.38 Max Datagram Size
configure voip > sip-definition
settings > t38-mx-datagram-sz
[T38MaxDatagramSize]
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 238.
T38 Fax Max Buffer
configure voip > sip-definition
settings > t38-fax-mx-buff
[T38FaxMaxBufferSize]
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 1024.
Detect Fax on Answer Tone
det-fax-on-ans-tone
[DetFaxOnAnswerTone]
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: The parameters is applicable only if the IsFaxUsed parameter
is set to 1 (T.38 Relay) or 3 (Fax Fallback).
T.38 Fax Session
configure voip > sip-definition
settings > t38-sess-imm-strt
[T38FaxSessionImmediateSta
rt]
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.
The 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
originating fax does not wait for an answer, but immediately starts
sending T.38 packets to the terminating fax machine.
Note: To enable No-Op packet transmission, use the NoOpEnable
and NoOpInterval parameters.

AudioCodes MSBG Series Specifications

General

Brand	AudioCodes
Model	MSBG Series
Category	Gateway
Language	English