Overview of channel structures

When creating MSPP channels with mspCreateChannel, you must specify channel configuration information in two structures:

Channel address structure

When applications create MSPP channels with mspCreateChannel, they specify the following parameters in the MSP_CHANNEL_ADDR structure:

typedef struct tag_MSP_CHANNEL_ADDR
{
    DWORD            size;
    DWORD            nBoard;        
    MSP_CHANNEL_TYPE channelType;
    DWORD            FilterAttribs;  
} MSP_CHANNEL_ADDR;

MSP_CHANNEL_ADDR

Dependent function: mspCreateChannel

Field

Type

Default

Units

Description

size

DWORD

N/A

N/A

Size of the address structure.

nBoard

DWORD

N/A

N/A

Channel location (board number).

channelType

MSP_CHANNEL_TYPE

N/A

N/A

Type of MSPP channel. Can be one of the following values:

  • G711FullDuplex

  • G723FullDuplex

  • G726FullDuplex

  • G729FullDuplex

  • FaxRelayFullDuplex

  • G711EncodeSimplex

  • G711DecodeSimplex

  • G723EncodeSimplex

  • G723DecodeSimplex

  • G726EncodeSimplex

  • G726DecodeSimplex

  • G729EncodeSimplex

  • G729DecodeSimplex

  • RTPSwitching

FilterAttribs

WORD

Null

N/A

Enables or disables functionality in the channels. The following value is defined:

MSP_FCN_ATTRIB_RFC2833: Enables inband DTMF carriage capability for the channel.

Channel parameter structures

Depending on the type of channel specified with the MSP_CHANNEL_TYPE parameter in the MSPP endpoint channel parameter structure, you must specify parameters in the following structures:

Channel type

Structure

Voice encode/decode (G.723.1, G.729A, G.726 simplex or duplex) or record channel

MSP_VOICE_CHANNEL_PARMS

T.38 fax

MSP_FAX_CHANNEL_PARMS

RTP switching

None. Only address parameters are required for switch channels.

This section discusses the Voice channel parameter structure and the T.38 fax relay channel parameter structure.