Fax Phase D Status Overview

T.30 Phase D (post-message procedure) status values indicate the status of a fax transmission and reception. This appendix lists the Phase D command values returned from the transmitter to the receiver, and the reply values returned from the receiver to the transmitter.

NOTE:

DFS_ALL and DFS_REMOTESUBADDR are Dialogic fax library terms, not T.30 protocol terminology.

To obtain Phase D status values, use the following fax extended attribute functions after a TFX_PHASED event or after the completion of the last page of a fax send or receive function.

• ATFX_PHDCMD( ) -- returns the Phase D command, which specifies the next phase of the fax session to the receiver.
• ATFX_PHDRPY( ) -- returns the Phase D reply from the receiver, which indicates the quality of the received transmission.

Table 24. Phase D Command Values - Transmitter to Receiver

Value	Description
DFS_EOP	End of Procedure -- Terminate fax session. Progress to Phase E and disconnect fax call.
DFS_MPS	Multi-page Signal -- End of current fax document page, more fax data to follow. Next fax document page is in the same format as the current page, so proceed directly to Phase C.
DFS_EOM	End of Message -- End of current fax document page, more fax data to follow. Return to Phase B and negotiate parameters for next fax document page.
DFS_POLL	A poll request was sent.
DFS_PRI_EOP	Request for operator intervention sent (PRI_EOP).
DFS_PRI_MPS	Request for operator intervention sent (PRI_MPS).
DFS_PRI_EOM	Request for operator intervention sent (PRI_EOM).

Most fax machines wait for the completed transmission of the final page of a fax session before sending an operator intervention request (PRI_EOP). The fax library responds to operator intervention requests from the remote station after receiving one of the following messages: PRI_EOP, PRI_MPS or PRI_EOM.

Table 25. Phase D Reply Values - Receiver to Transmitter

Value	Description
DFS_MCF	Message confirmation -- valid fax image received, ready for more pages.
DFS_RTN	Retrain negative -- bad fax image received, retrain and resend image.
DFS_RTP	Retrain positive -- valid fax image received but retraining required (transmitter determines whether lower baud rate is needed for continued successful reception).
DFS_PIP	Procedure interrupt positive -- operator intervention request.
DFS_PIN	Procedure interrupt negative -- operator intervention request.

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