6.2.4 Setting Out-of-Band Mode

In out-of-band mode, the DTMF audio is automatically clamped (muted) and DTMF digits are not sent in the RTP packets. To set up a channel for out-of-band mode, do the following:

1. Open a channel using ipm_Open("ipmB1C1",NULL,EV_SYNC)
2. Set the mode via the IPM_PARM_INFO structure and ipm_SetParm( ) as shown below:

    IPM_PARM_INFO parmInfo;
    unsigned long ulParmValue = DTMFXFERMODE_OUTOFBAND;
    parmInfo.eParm = PARMCH_DTMFXFERMODE;
    parmInfo.pvParmValue = &ulParmValue
    ipm_SetParm(chdev, &parmInfo, EV_ASYNC) 

3. Call ipm_ReceiveDigits(chdev) to have digits reported to the application and clamped from the RTP packets.

To change back to in-band mode, set the PARMCH_DTMFXFERMODE parameter to DTMFXFERMODE_INBAND.

Figure 5 shows a scenario diagram for setting out-of-band mode.

Figure 5. Out-of-Band Mode Scenario Diagram

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