/etc/hylafax/config is in hylafax-server 3:6.0.6-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 | #ContCoverPage:         "etc/cover.templ"
#DestControls:		"etc/destctrls"
#DialStringRules:       "etc/dialrules"
#QualifyCID:		"etc/cid"
#QualifyTSI:		"etc/tsi"
#ServerTracing:		0x08501
InternationalPrefix:	00
 |