You can control ECM support via the FAX CLASS 2 AT-command set or via Global Dialogic® Diva® TTY configuration options.
If you use global Diva TTY configuration options to enable ECM support, the Dialogic® Diva® Media Board will use ECM mode for document transfer, if supported by the opposite side.
Diva Media Boards use their internal memory to store document data. They retrieve data for ECM re-transmissions from this internal buffer (up to 64 Kbytes for every channel). This reduces the host CPU load and increases the reliability of the fax transmission.