While creating a new fax every users gets a drop down on their ring central where they can select a number that they want to use for sending Fax .Mostly users select their own primary number but in some cases they are required to select a different number which is dedicated to the entire office for sending Faxes .
If the user selects any other number other than their Primary number and sends Fax then it is also updating the Fax number under outbound calls/Fax section on Ring central Admin side.
So if my Primary number is 555-555-5555 but while sending Fax if I select 666-666-6666 from drop down then it changes number on ring central admin Fax section for my profile to 666-666-6666 . Only way to reverse it is select my primary number from drop down again to reset settings .
The admin side should not get affected by the number we select on user's ring central app.I was told that this is normal RC behavior by multiple RC reps .