The DevSpecific packet is transmitted from a TAPI client to a TAPI server in a remote procedure call. The function is used as a general extension mechanism to enable service providers to provide access to features that are not described in other operations. The meanings of the extensions are device-specific, and to take advantage of these extensions, the application MUST be fully aware of them.
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Req_Func |
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Reserved1 |
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dwRequestID |
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lpContext |
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hLine |
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dwAddressID |
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hCall |
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lpParamsContext |
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lpParams |
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dwSize |
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Reserved2 |
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Reserved3 |
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Reserved4 |
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Reserved5 |
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Reserved6 |
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VarData (variable) |
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... |
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Req_Func (4 bytes): An unsigned 32-bit integer. The identifier of the function that will be invoked on the remote server. This value MUST be set to 13.
Return Values
On completion of ClientRequest, this field contains the result of the encapsulated telephony request. A nonzero request ID value indicates that the request is in progress and will complete asynchronously and a LINEERR_Constants value indicates synchronous failure.
Returns a positive request identifier if the function will be completed asynchronously or a negative error number if an error occurs. The dwParam2 parameter of the corresponding LINE_REPLY packet is zero if the function succeeds, or it is a negative error number if an error occurs. If the client specified a nonzero value in the dwRequestID field of the packet, the same value MUST be used for the returned positive request identifier. Common return values are as follows:
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Name |
Value |
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LINEERR_INVALLINEHANDLE |
0x8000002B |
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LINEERR_OPERATIONUNAVAIL |
0x80000049 |
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LINEERR_INVALADDRESSID |
0x80000011 |
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LINEERR_OPERATIONFAILED |
0x80000048 |
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LINEERR_NOMEM |
0x80000044 |
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LINEERR_RESOURCEUNAVAIL |
0x8000004B |
Reserved1 (4 bytes): An unsigned 32-bit integer. MUST be set to zero when sent and MUST be ignored on receipt.
dwRequestID (4 bytes): An unsigned 32-bit integer. The identifier of the asynchronous request.
lpContext (4 bytes): An unsigned 32-bit integer. The opaque, client-specified value that is used by the client upon request completion; MUST be returned by the server in the request completion packet.
hLine (4 bytes): An HLINE. The handle to a line device. This field MUST have been obtained by sending the Open packet. This parameter is required.
dwAddressID (4 bytes): An unsigned 32-bit integer. The address on the specified line to be operated on. An address identifier is permanently associated with an address; the identifier MUST remain constant across operating system upgrades. A valid value of dwAddressID is in the range 0 to dwNumAddresses –1. The client obtains dwNumAddresses from the LINEDEVCAPSobtained by sending a GetDevCapspacket to the remote server.
hCall (4 bytes): An HCALL. The handle to a call. This parameter is optional, but if it is specified, the call it represents MUST belong to the hLine line device. One way of obtaining a valid hCall is by sending the MakeCall packet. The call state of hCall is device specific.
lpParamsContext (4 bytes): An unsigned 32-bit integer. The opaque, client-specified value that is used by the client upon request completion; MUST be returned by the server in the request completion packet.
lpParams (4 bytes): An unsigned 32-bit integer. The offset, in bytes, in the VarData field of a parameter block. The format of this parameter block is device-specific and its contents are passed by TAPI, to or from the TSP.
dwSize (4 bytes): An unsigned 32-bit integer. The size, in bytes, of the parameter block that is indicated in the lpParams field.
Reserved2 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
Reserved3 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
Reserved4 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
Reserved5 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
Reserved6 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
VarData (variable): Contains a parameter block that is indicated in the lpParams field. The format of this parameter block is device-specific and its contents are passed by TAPI, to or from the TSP.