PRE Translation is easy if thats the way you want to go. You have to setup 2 SCL's (Used to translate the dialed leading digit) a default one and one for your fax so an example
SCL 0
stor 0 0 <-- drops the leading 0 and replaces with 0
stor 1 1 <-- drops the leading 1 and replaces with 1
stor 2 2
all the way to
stor 9 9
SCL 1
stor 0 90 <-- drops the leading 0 and replaces with 90
stor 1 91 <-- drops the leading 1 and replaces with 91
stor 2 92
all the way to
stor 9 99
Then PRE 0 set as XLAT 0
PRE 1 set as XLAT 1
In LD 15 (FTR) you need to set PREO to 1 to enable the feature
All sets would default to XLST 0 so digits are replaced with same digit as per SCL 0. Whereas your fax you change to XLST 1 in the set config so that digits would be prefixed with 9 as per SCL 1. Most config is in LD 18 (SCL, PRE) you may need to do the CDB bit first cant remember, this will be detailed in the Freature Guides under pre-translations.