4.13.7. Getting Notification of T.38 Status Changes

The application can receive notification of underlying T.38 status changes including: tone detection on the TDM or IP sides, T.38 capability frame status, T.38 information frame status, and T.38 HDLC frame status. The events for this notification must be enabled; see Section 4.14, Enabling and Disabling Unsolicited Notification Events for information on enabling T.38 fax status changes (EXTENSIONEVT_T38_STATUS).

Once these events are enabled, when the T.38 status change occurs, the application receives a GCEV_EXTENSION event. The EXTENSIONEVTBLK structure pointed to by the extevtdatap pointer within the GCEV_EXTENSION event will contain the following information:

• extID - IPEXTID_FOIP
• A GC_PARM_BLK that contains information about the T.38 status change. The GC_PARM_BLK can contain the following parameter set IDs and parameter IDs:
  • IPSET_TDM_TONEDET - A parameter set identifying a tone detected on the TDM side as identified by one of the following parameter IDs:
    • IPPARM_TDMDET_CED - CED tone detected from TDM side.
    • IPPARM_TDMDET_CNG - CNG tone detected from TDM side.
    • IPPARM_TDMDET_V21 - V.21 tone detected from TDM side.

    Note: The parameter value field in the GC_PARM_BLK in each case is unused (NULL).

  • IPSET_T38_TONEDET - A parameter set identifying a tone detected on the IP side as identified by one of the following parameter IDs:
    • IPPARM_T38DET_CED - CED tone detected from IP side.
    • IPPARM_T38DET_CNG - CNG tone detected from IP side.
    • IPPARM_T38DET_V21 - V21 tone detected from IP side.

    Note: The parameter value field in the GC_PARM_BLK in each case is unused (NULL).

  • IPSET_T38CAPFRAME_STATUS - A parameter set identifying the T.38 capability frame type identified by one of the following parameter IDs:
    • IPPARM_T38CAPFRAME_TX_DIS_DTC
    • IPPARM_T38CAPFRAME_TX_DCS
    • IPPARM_T38CAPFRAME_TX_CTC
    • IPPARM_T38CAPFRAME_RX_DIX_DTC
    • IPPARM_T38CAPFRAME_RX_DCS
    • IPPARM_T38CAPFRAME_RX_CTC

    Note: The parameter value field in the GC_PARM_BLK in each case includes the capability frame status structure, IPM_T38CAPFRAM_STATUS_INFO.

  • IPSET_T38INFOFRAME_STATUS - A parameter set identifying the T.38 information frame type identified by one of the following parameter IDs:
    • IPPARM_T38INFOFRAME_TX_SUB
    • IPPARM_T38INFOFRAME_RX_SUB
    • IPPARM_T38INFOFRAME_TX_SEP
    • IPPARM_T38INFOFRAME_RX_SEP
    • IPPARM_T38INFOFRAME_TX_PWD
    • IPPARM_T38INFOFRAME_RX_PWD
    • IPPARM_T38INFOFRAME_TX_TSI
    • IPPARM_T38INFOFRAME_RX_TSI
    • IPPARM_T38INFOFRAME_TX_CSI
    • IPPARM_T38INFOFRAME_RX_CSI
    • IPPARM_T38INFOFRAME_TX_CIG
    • IPPARM_T38INFOFRAME_RX_CIG

    Note: The parameter value field in this GC_PARM_BLK in each case includes the frame buffer.

  • IPSET_T38HDLCFRAME_STATUS - A parameter set identifying the T.38 HDLC frame type identified by one of the following parameter IDs:
    • IPPARM_T38HDLCFRAME_TX
    • IPPARM_T38HDLCFRAME_RX

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