T.38 Fax Fallback To G.711; T.38 With Error Correction Mode; List Trace And List Measurement - Avaya G450 Overview And Specification

T.38 Fax Fallback to G.711

The T.38 Fax Fallback to G.711 feature provides the functionality for enterprise networks managed
by Communication Manager to interoperate with older Verizon networks that do not support T.38
Fax for fax transport. A new codec type, T.38 Fax with Fallback to G.711 Pass-Through, is added
to the IP codec set for Fax mode.
T.38 Fax Fallback to G.711 operates in the following way:
• The call connection is signaled for a standard T.38 fax relay.
• If T.38 fax relay is successfully negotiated, Communication Manager issues a re-INVITE to
G.711 mode.
• The fax call is in G.711 mode until the user disconnects. This feature works only over SIP
trunks.
For more information about the T.38 Fax Fallback to G.711 feature, see Avaya Aura
Communication Manager Feature Description and Implementation.

T.38 with Error Correction mode

T.38 with Error Correction mode (ECM) corrects errors without retransmitting multiple pages.
Communication Manager instructs Branch Gateway to use ECM as a part of T.38 Fax exchange in
the following cases:
• The local media gateway indicates support for this feature through exchange capability.
• The IP codec set is set to T.38-standard.
• ECM is enabled.
Fax machines with the memory capacity to store page data can use ECM for error-free page
transmission. When ECM is enabled, a fax page is transmitted in a series of blocks that contain
frames with data packets. After receiving data for a complete page, a receiving fax machine
notifies the transmitting fax machine of any frames with errors. The transmitting fax machine then
retransmits the specified frames. This process is repeated until all frames are received without
errors.
If the receiving fax machine is unable to receive an error-free page, the fax transmission fails and
one of fax machines is disconnected.
For more information about the T.38 with ECM feature, see Administering Network Connectivity on
®
Avaya Aura Communication Manager.

List Trace and List Measurement

The List Trace and List Measurement commands provide additional performance and diagnostic
information for V.150 / Modem-over-IP calls.
April 2020 Avaya G450 Branch Gateway Overview and Specification
Comments on this document? infodev@avaya.com
G450 Branch Gateway features
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