If you want to use your Brother machine to send and receive faxes over MagicJack, we recommend you contact MagicJack and ask them which modem speed they recommend for faxing.
Set the Brother machine's modem speed to their recommendation.
Following these steps:
Press (Settings).
Press All Settings.
Press the Up or Down arrow key to display Initial Setup.
Press Initial Setup.
Press the Up or Down arrow key to display Compatibility.
Press Compatibility.
Press the modem speed you want to use.
You can choose High, Normal or Basic (for VoIP).
High sets the machine's modem speed at 33,600 bps.
Normal sets the machine's modem speed at 14,400 bps.
Basic (for VoIP) sets the machine's modem speed at 9,600 bps.
When you change the compatibility to Basic(for VoIP), your Brother machine's Error Correction Mode (ECM) is turned off when sending or receiving black and white faxes. ECM cannot be turned off for color faxing.