Asterisk - The Open Source Telephony Project  18.5.0
res_fax.conf
; Generic Fax Application configuration

[general]
; Maximum Transmission Rate
; Possible values are { 2400 | 4800 | 7200 | 9600 | 12000 | 14400 }
; Set this value to the maximum desired transfer rate.  Default: 14400
;maxrate=14400

; Minimum Transmission Rate
; Possible values are { 2400 | 4800 | 7200 | 9600 | 12000 | 14400 }
; Set this value to the minimum desired transfer rate.  Default: 4800
;minrate=4800

; Send Progress/Status events to manager session
; Manager events with 'call' class permissions will receive events indicating the
; steps to initiate a fax session.  Fax completion events are always sent to manager
; sessions with 'call' class permissions, regardless of the value of this option.
; Default: no
statusevents=yes

; modem capabilities
; Possible values are { v17 | v27 | v29 }
; Set this value to modify the default modem options.  Default: v17,v27,v29
;modems=v17,v27,v29

; Enable/disable T.30 ECM (error correction mode) by default.
; Default: Enabled
;ecm=yes

; T.38 Negotiation Timeout in milliseconds
; Default: 5000
t38timeout=5000