Introduction

Use the following parameters to configure the PRI with Fax settings.

FAX-Settings

ParameterDescription
Enable-FAX-T38Use this setting to enable or disable the FAX T38 feature. 
Fax-Bit-Rate

This field determines the bit rate in bps. The maximum rate is 14400 bps. 

Note: Super G3/G4 Fax is not supported.

Fax-TCFThis field is used to select the method for the Training Check Function signal. Options are Local or Transferred (from the emitting gateway to the receiving gateway). 
Fax-OptionsOptions include Default, BitRemoval, TransMMR, or JBIG Transcoding. 
UDP-Max-BufferDefault is 1024. The range is 200 to 4096 octets. Enter the maximum number of octets that can be stored on the remote device before an overflow condition occurs. 
UDP-Max-Datagram-Size

Default is 256. The range is 200 to 512 bytes. Enter the maximum size of a UDP Transport Layer (UDPTL) packet or the maximum size of the payload within an RTP packet that can be accepted by the remote side. 

Fax-Error-CorrectionDefault is Redundancy. Choose the error correction method used by the Fax machine.
MAX-T38-SessionLimits the number of fax sessions allowed. On 4808DB, the max limit is 5. On 4808 the Max limit is set to 9. Since the tone-detection and Fax is done in the software, this is to limit the CPU resources.
Ignore-FAX-Over-AudioIf enabled, any invite that comes with mutiple media in SDP, one for voice and one of T.38, T.38 media will be ignored. This is special case for some soft switch.
Offer-T38-OutgoingThe Fax-over-IP recommendation is to have the Receiving T.38 gateway always offer the T.38 if FAX is detected.  Some gateway implementations break that and do not offer T.38. When this is true, even the sending gateway will offer the T.38. 
Enable-ADTRAN-T38-Interop

Default is False. When True, Redundance Recovery mode is forced for better interop.