One or more pages was confirmed as RTN

You may see this error message under “detailed fax status field” on sent fax record and fax status is “not delivered.”

Reason for this error:
A retrain negative (RTN) message is a result of discarded data during the fax transmission due to interpage timing protocol. If a retrain message is received during the fax transmission eFax Developer will propose a new bit rate. It is up to the receiving modem to accept the newly proposed bit rate or ask for another retrain sequence. If both parties can not negotiate a bit rate the result will be “One or more pages was confirmed as RTN” failure message.

To resolve: This should be investigated by the other fax carrier that is returning this error message.