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Use the lineSetHSCSDState function to set the non-transparent High Speed Circuit Switched Data (HSCSD) configuration prior to a data call. During a call, the air interface rate and channel count can be changed.

  HLINE hLine,
  DWORD dwChannelsIn,
  DWORD dwMaxChannelsIn,
  DWORD dwChannelCodings,
  DWORD dwAirInterfaceRate


  • hLine
    The line device handle. The line device handle must have been previously obtained by a call to lineOpen with the proper TAPI device ID specified and a device-specific extension version successfully negotiated with lineNegotiateExtVersion. For more information about lineNegotiateExtVersion and lineOpen, see the TAPI Functions API Reference topics on MSDN.

  • dwChannelsIn
    Indicates the initial number of downstream radio channels in the next call.

    Note   The number of upstream channels is determined by the network.

  • dwMaxChannelsIn
    Indicates the maximum number of downstream radio channels that will be requested in the next call. If zero, the Windows Mobile-based device cannot dynamically change dwChannelsIn during the data call.

  • dwChannelCodings
    Indicates the possible per-channel speeds at which the Windows Mobile-based device can communicate with the network. See the Channel Rates constants for possible values.

  • dwAirInterfaceRate
    Indicates the speed at which the Windows Mobile-based device should communicate with the base station. See the lpdwAirInterfaceRate parameter of the lineGetHSCSDState function for possible values.

    Note   Due to RLP error link correction, the request air interface rate should be higher than the desired land link rate between the landline IWF and the connection destination.

Return Values

Returns a positive request identifier if the function is completed asynchronously, or a negative error number if an error occurs. The dwParam2 parameter of the corresponding LINE_REPLY message is zero if the function succeeds or it is a negative error number if an error occurs. The following are possible return values:



This is a privileged function.

Not implemented for CDMA.


Pocket PC: Pocket PC 2002 and later.
Smartphone: Smartphone 2002 and later.
OS Versions: Windows CE 3.0 and later.
Header: Extapi.h.
Library: Cellcore.lib.

See Also

Extended TAPI Functions | lineGetHSCSDState

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