MFC-640CW FAQs & Troubleshooting MFC-640CW Not your product? Sort by: Updated Date Popularity 3 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? 3. 05/24/2006 I cannot receive a color fax. Why? Fax FAQs & Troubleshooting