Lexmark MX811
Open a Web browser, and then type the printer IP address in the address field.
Notes:
Click Settings > Fax Settings > Analog Fax Setup.
In the Fax Name field, type the name to be printed on all outgoing faxes.
In the Fax Number field, enter the printer fax number.
Click Submit.
General Fax Setup Troubleshooting for Most Lexmark MFPs (2011)
Set up your printer to send faxes using an adapter for non-RJ11 wall jacks.