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T38 Fax

Navigation: Call Management > Extensions > Edit Extension > SIP T38 Fax

The settings on this tab are only accessible if Re-invite Supported and Fax Transport Support are selected on the VoIP tab.

Fax relay is only supported on IP500 V2 systems with IP500 VCM, IP500 VCM V2 and or IP500 Combo cards. Fax relay is not supported on Server Edition.

These settings are not mergeable. Changes to these settings will require a reboot of the system.

Field Description
Use Default Values Default = On.

If selected, all the fields are set to their default values and greyed out.

T38 Fax Version Default = 3.

The system can support Versions 0, 1, 2 and 3. During fax relay, the two gateways will negotiate to use the highest version which they both support.

Transport Default = UDPTL (fixed).

Currently only UDPTL is supported. TCP and RTP transport are not supported

For UDPTL, redundancy error correction is supported. Forward Error Correction (FEC) is not supported.

Redundancy

Redundancy sends additional fax packets in order to increase the reliability. However increased redundancy increases the bandwidth required for the fax transport.

Low Speed Default = 0 (No redundancy). Range = 0 to 5. Sets the number of redundant T38 fax packets that should be sent for low speed V.21 T.30 fax transmissions.
High Speed Default = 0 (No redundancy). Range = 0 to 5. Sets the number of redundant T38 fax packets that should be sent for V.17, V.27 and V.28 fax transmissions.
 
TCF Method Default = Trans TCF.

TCF = Training Check Frame.

Max Bit Rate (bps) Default = 14400. Lower rates can be selected if the current rate is not supported by the fax equipment or is found to not be reliable.
EFlag Start Timer (msecs) Default = 2600.
EFlag Stop Timer (msecs) Default = 2300.
Tx Network Timeout (secs) Default = 150.
Scan Line Fix-up Default = On.
TFOP Enhancement Default = On.
Disable T30 ECM Default = Off. When selected, disabled the T.30 Error Correction Mode used for fax transmission.
Disable EFlags For First DIS Default = Off.
Disable T30 MR Compression Default = Off.
NSF Override

Default = Off. If selected, the NSF (Non-Standard Facility) information sent by the T38 device can be overridden using the values in the fields below

Country Code Default = 0.
Vendor Code Default = 0.