Matrix PRASAR UCS - Page 357

348 Matrix PRASAR UCS System Manual
• 'Pass Through' and 'T.38' will work only if the peer devices also support the same option.
• If you select 'Pass through' as Fax type, you must disable 'Silence Suppression'.
• If the fax sent using T.38 is rejected, PRASAR UCS will use Pass Through for sending the Fax.
• FAX is not supported when Transcoding is set as the RTP Mode.
• The below mentioned parameters are relevant only if you have selected T.38 as the Fax Type for Fax over
IP. Receiving a good quality fax over SIP trunk depends on high 'Eye Quality Monitor' (EQM). The higher
the Eye Quality Monitor, the better the Fax quality. To improve the quality of T.38 fax reception, you may
configure the below parameters:
• T.38 Fax Parameter - Version: Configure this parameter as supported by the Remote Peer, which may
be a Proxy Server or a SIP Device. While sending a fax, the Version will be sent in the re-INVITE
Message to the Remote Peer. While receiving a fax PRASAR UCS will accept a Version equal to or
less than the configured Version.
A different Version can be configured for each SIP Trunk. This is useful when you have proxy SIP
Trunks registered with different service providers supporting different versions.
The valid range for the Version is from 0 to 3. By default Version when Fax Type is T.38 (UDPTL) is 0
and when Fax Type is T.38 (RTP) it is 1.
• T.38 Fax Parameter - Max Rate (Kbps): This parameter controls the Fax image transfer speed. As
EQM is inversely proportional to Fax Max Rate, if you receive poor quality fax, the Fax Max Rate
should be reduced. The default Max rate is 14.4 kbps.
• Signal Redundancy Level: The Fax Signal Level is redundancy level for output Image, which can be
None, 1 or 2.
Fax Signal transfer speed is inversely proportional to this parameter. If this parameter is low then fax is
transferred faster. EQM is directly proportional to this parameter. If this parameter is high, good quality
fax can be achieved.
Increase the Fax Signal Level, if the quality of fax does not improve with Fax Max Rate.
Level None means no redundancy. By default Signal Redundancy level is set to 2.
• Data Redundancy Level: This is a redundancy level for T.38 control data. Fax Data Level can be set
as None, 1 or 2. Level None means no redundancy. The higher the Redundancy level, the slower
would be the fax transmission.
EQM is directly proportional to this parameter. The higher the Fax Data Redundancy Level, the better
the EQM. By default, Data Redundancy Level is set to None.
• Pass Through FAX Codec: When the Fax option is selected as Pass Through, you must configure the
Pass Through FAX Codec as supported by the Remote Peer. The Remote Peer may be a Proxy Server
or a SIP Device.
• You may select the Codec as G.711 A-law or G.711 LawWhile sending a fax this Codec is sent in
the re-INVITE message to the Remote Peer, but while receiving a fax PRASAR UCS will accept the fax
with any Codec.
• Click Submit.