sip.conf

[general]
context=default                 ; Default context for incoming calls
port=5060
bindaddr=0.0.0.0
tos=lowdelay
disallow=all
allow=ulaw
allow=g729

externaddr = XXXX
localnet=XXXXX/255.255.0.0


register => XXXXXXXXXXXXXXXX

t38pt_udptl = yes            ; Enables T.38 with FEC error correction.
faxdetect = yes               ; Default 'no', 'yes' enables both CNG and T.38 detection

[flowroute] ;keep this lowercase, do not change format
type=friend
secret=XXXXXXXXXXXX
username=XXXXXXXXXXXXX
host=sip.flowroute.com
dtmfmode=rfc2833
context=flowroute-incoming
canreinvite=no
allow=ulaw
allow=g729
insecure=port,invite
fromdomain=sip.flowroute.com
t38pt_udptl = yes