Hi tuanquan,
Thank you for using the Xerox forum.
I would suggest that you review the following online Administrators guide chapter 8 which has directions for many fax default settings as you can see in the below images.
http://download.support.xerox.com/pub/docs/WC58XA/userdocs/any-os/en_GB/wc58xa_wc58xb_sag_en-us.pdf
If that does not resolve your issue you may consider contacting our specific product support experts at the following link:
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