T.38 with Error Correction mode (ECM) corrects errors without retransmitting multiple pages.

Communication Manager instructs Branch Gateway to use ECM as a part of T.38 Fax exchange in the following cases:

• The local media gateway indicates support for this feature through exchange capability.

• The IP codec set is set to T.38-standard.

• ECM is enabled.

Fax machines with the memory capacity to store page data can use ECM for error-free page transmission. When ECM is enabled, a fax page is transmitted in a series of blocks that contain frames with data packets. After receiving data for a complete page, a receiving fax machine notifies the transmitting fax machine of any frames with errors. The transmitting fax machine then retransmits the specified frames. This process is repeated until all frames are received without errors.

If the receiving fax machine is unable to receive an error-free page, the fax transmission fails and one of fax machines is disconnected.

For more information about the T.38 with ECM feature, see Administering Network Connectivity on Avaya Aura® Communication Manager.