MFC-7880DN FAQs & Troubleshooting MFC-7880DN Not your product? Sort by: Updated Date Popularity 2 Results 1. 09/04/2015 I am experiencing problems sending a fax. 2. 10/05/2012 When I send a fax from the machine, an error "not register." or "not registered." is displayed. Fax FAQs & Troubleshooting