5.4. Issuing a Receive Fax Function

• 5.4.1. Receive Fax Issued by the Receiver
• 5.4.2. Receive Fax Issued by the Transmitter
• 5.4.3. Status of Fax Reception

When the initial fax connection is made between the caller and the called applications, the caller application is initially set to be the fax transmitter and the called application is initially set to be the fax receiver, as in a normal fax transmission.

5.4.1. Receive Fax Issued by the Receiver

When the receiver issues fx_rcvfax( ) and the transmitter does not poll, the call progresses as in a normal fax transmission; that is, the transmitter sends fax data to the receiver.

If the transmitter polls, the poll bit in the fx_rcvfax( ) function issued by the receiver indicates whether a poll by the transmitter is valid.

Polling Invalid. If the poll bit is set to DF_NOPOLL, the receiver application remains the receiver of the fax data. A poll by the transmitter is invalid; the fx_rcvfax( ) function fails and the fax session is terminated. In this case, ATDV_LASTERR( ) returns an EFX_DISCONNECT error.

 
If the receiver's poll bit is set to DF_NOPOLL, the transmitter can only send fax data to the receiver, as in a normal fax transmission.

Polling Valid. If the poll bit is set to DF_POLL and the transmitter application polls, the receiver's fx_rcvfax( ) function returns a 0 in synchronous mode or a TFX_FAXRECV event occurs in asynchronous mode. The receiver application calls the fax extended attribute ATFX_TERMMSK( ) and determines that a poll has occurred (TM_POLLED). The receiver application can now become the fax transmitter.

 
The fax session remains active and the original receiver must immediately issue a send function to complete the poll and become the new fax transmitter.
 
If the transmitter does not poll, the receiver's fx_rcvfax( ) function completes as it would for a normal fax transmission.


5.4.2. Receive Fax Issued by the Transmitter

When the transmitter issues the fx_rcvfax( ) function, this indicates a poll request; that is, the transmitter application wishes to be a fax receiver.

Polling Valid. If the poll bit is set to DF_POLL on the receiver side, polling is valid. The initial receiver and transmitter switch roles. The fax is sent to the new fax receiver.

Polling Invalid. If the poll bit is set to DF_NOPOLL on the receiver side, polling is invalid. The fx_rcvfax( ) function in the transmitter application fails and the fax session is terminated. In this case, ATDV_LASTERR( ) returns a EFX_NOPOLL error.

5.4.3. Status of Fax Reception

Status information on the fax reception is available using the fax extended attribute functions.

• During fax reception, the state of the channel device is set to CS_RECVFAX. To obtain the current state of the channel device, call ATFX_STATE( ).
• To obtain the final transfer Phase D status, call ATFX_PHDCMD( ) and ATFX_PHDRPY( ). For more information on Phase D status values, see Appendix B.

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