MFC-6800 FAQs & Troubleshooting MFC-6800 Not your product? Sort by: Updated Date Popularity 2 Results 1. 12/15/2014 I am using Voice Over Internet Protocol (VoIP) and cannot send and/or receive faxes. What can I do? 2. 05/10/2013 Why doesn't the machine answer when receiving a call? Fax FAQs & Troubleshooting