Not native but there are 3rd party apps. Sorry, I'm on the run and can't look up the links but I used eOffice for a while and it had that capability. Not sure but I think Google Docs does too. I think those fax apps all upload docs over-the-air to a fax server and then deliver from there. Until someone comes along with specific links, you might just check Google with "fax from Blackberry" or something similar.
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