Fax Configuration Settings; Sip General Parameters - AudioCodes MP-11x Configuration Manual

Audiocodes T.38 FAX Configuration Guide

2. FAX Configuration Settings

Per the requirements of the tested solution, the values shown in this guide are in general
the defaults for the basic T.38 FAX. Because the AudioCodes MGW supports several
alternate ways of transporting FAX and Modem data (Transparent, Transparent with
events, Bypass, NSE, V.152, etc.), there are many settings and combinations of settings
that are best left to solving specific situations. Complete information about these non-
standard values is included in the User‟s manual referenced above.
If you are using the default settings and you are still experiencing problems with T.38
FAX, check first the end to end call flow. In previous releases, most of these FAX issues
result from issues revolve around routing, and or the proper server settings for Avaya
TON/NPI headers.
DO NOT CHANGE FAX SETTINGS THAT ARE NOT WELL UNDERSTOOD in an
effort to fix a specific FAX failure since that will cause an unsupported configuration to
be placed in service with possible support issues down the road.
Additionally, make sure that the software release running on the Audiocodes MP-1xx
matches exactly the approved load line up for the release. Occasionally, the devices
shipped from stock have been manufactured prior to the final release date or have been in
a warehouse for so long that there is a good chance that the version is not correct. IT IS
THE RESPONSIBILITY OF THE INSTALLER to check and verify that the software
placed in service is in accordance with the solution as it was tested for interoperability.
2.1

SIP General Parameters

The values shown are basic T.38 examples. Other than some that are highlighted below,
most of the default values are usually used in the SIP General Parameters.
IsFaxUsed = 1
Fax Signaling Method
In the T.38 Relay Mode, upon detection of a fax signal the terminating device negotiates
T.38 capabilities using a SIP Re-INVITE message. If the far end device doesn't support
T.38, the fax fails. In this mode, the parameter FaxTransportMode is ignored. To
configure T.38 mode using SIP Re-INVITE messages, make the following setting:
[0] No Fax = No fax negotiation using SIP signaling. Fax transport
method is according to the parameter FaxTransportMode (default).
[1] T.38 Relay = Initiates T.38 fax relay.
[2] G.711 Transport = Initiates fax / modem using the coder G.711 Alaw/
μ-law with adaptations (refer to User‟s Manual).
[3] Fax Fallback = Initiates T.38 fax relay. If the T.38 negotiation fails,
the device re-initiates a fax session using the coder G.711 A-law/μ-law
with adaptations (refer to the Note in the User Manual).
Verizon T.38 FAX Configuration Guide for AudioCodes MP-11x
Version 1.0
Page 10
30-APR- 2011
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