AudioCodes MEDIAPACK VERSION 6.2 - Manual (Page 95)

Version 6.2 95 December 2010
SIP Release Notes 1. What's New in Release 6.2
1.11.3 Media New Parameters
The table below describes the new media parameters for Release 6.2.
Notes: These parameters are applicable only to the Gateway application.
Table 1-7: New Media Parameters for Release 6.2
Parameter Description
[T38FaxSessionImmediateStart] Enables fax transmission of T.38 “no-signal” packets to the
terminating fax machine.
[0] Disable (default)
[1] Enable
This is used for transmission from fax machines (connected to
the device) located inside a Network Address Translation
(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.
T38 Version
[SIPT38Version] Selects the T.38 fax relay version.
[-1] Not Configured = No T.38 (default)
[0] T.38 version 0 (default)
[3] T.38 version 3 = T.38 Version 3 (V.34 over T.38 support)