2.2.4.1.3.3 AgentSpecific

The AgentSpecific packet is transmitted from a TAPI client to a TAPI server in a remote procedure call. Sending this packet allows the application to access proprietary handler-specific functions of the agent handler that is associated with the address.

The meaning of the extensions are specific to the agent handler. Each set of agent-related extensions is identified by a universally unique 128-bit extension ID that MUST be obtained, along with the specification for the extension, from the promulgator of that extension (usually the author of the agent handler software on the telephony server).

The list of extensions that are supported by the agent handler is obtained from the LINEAGENTCAPS packet that is returned by the GetAgentCaps packet.


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Req_Func

Reserved1

dwRequestID

lpContext

hLine

dwAddressID

dwAgentExtensionIDIndex

lpParamsContext

lpParams

dwSize

Reserved2

Reserved3

Reserved4

Reserved5

Reserved6

VarData (variable)

...

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 6.

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. If the client specified a nonzero value in the dwRequestID field of the packet, the same MUST be used as the value for the returned positive request identifier.

Common return values are as follows:

Name

Value

LINEERR_INVALADDRESSID

0x80000011

LINEERR_INVALAGENTID

0x80000057

LINEERR_INVALLINEHANDLE

0x8000002B

LINEERR_INVALPARAM

0x80000032

LINEERR_INVALPOINTER

0x80000035

LINEERR_NOMEM

0x80000044

LINEERR_OPERATIONFAILED

0x80000048

LINEERR_OPERATIONUNAVAIL

0x80000049

LINEERR_RESOURCEUNAVAIL

0x8000004B

LINEERR_STRUCTURETOOSMALL

0x8000004D

LINEERR_UNINITIALIZED

0x80000050

Additional return values are specific to the agent handler.

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.

Value

Meaning

0x00000000

The server MUST generate a unique positive request ID to return as the Ack_ReturnValue.

0x00000001 — 0x7FFFFFFF

The server MUST use this value instead of generating a unique positive request ID.

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 the open line device. This field MUST have been obtained by sending the Open packet.

dwAddressID (4 bytes): An unsigned 32-bit integer. The address on the open line device. An address identifier is permanently associated with an address; the identifier remains constant across operating system upgrades. A valid value of dwAddressID is in the range 0 to dwNumAddresses –1. The client obtains dwNumAddresses from the LINEDEVCAPS obtained by sending a GetDevCaps packet to the remote server.

dwAgentExtensionIDIndex (4 bytes): An unsigned 32-bit integer. The position in the ExtensionIDList packet in LINEAGENTCAPS of the agent handler extension being invoked. A valid value of dwAgentExtensionIDIndex is in the range 0 to dwNumAgentExtensionIDs – 1. The client obtains dwNumAgentExtensionIDs from the LINEAGENTCAPS obtained by sending a GetAgentCaps packet to the remote server.

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 and from the agent handler application on the telephony server. This parameter block MUST specify the function to invoke and include sufficient room for data to be returned.

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 corresponds to the proprietary handler-specific functions of the agent handler. This data is opaque to the protocol.

The contents of this field MUST be DWORD-aligned, as specified in [MS-DTYP] section 2.2.9.