<div class="content"><p>The DevSpecific packet is transmitted from a TAPI <a href="489de77f-16d8-4c4f-939a-f795e8b42893#gt_60e0e1fa-66fe-41e1-b5e3-ceab97e53506" data-linktype="relative-path">client</a> to a TAPI <a href="489de77f-16d8-4c4f-939a-f795e8b42893#gt_434b0234-e970-4e8c-bdfa-e16a30d96703" data-linktype="relative-path">server</a> in a <a href="489de77f-16d8-4c4f-939a-f795e8b42893#gt_8a7f6700-8311-45bc-af10-82e10accd331" data-linktype="relative-path">remote procedure call</a>. 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.</p><table>
 <tbody><tr>
  <th><p><br/>0</p></th>
  <th><p><br/>1</p></th>
  <th><p><br/>2</p></th>
  <th><p><br/>3</p></th>
  <th><p><br/>4</p></th>
  <th><p><br/>5</p></th>
  <th><p><br/>6</p></th>
  <th><p><br/>7</p></th>
  <th><p><br/>8</p></th>
  <th><p><br/>9</p></th>
  <th><p>1<br/>0</p></th>
  <th><p><br/>1</p></th>
  <th><p><br/>2</p></th>
  <th><p><br/>3</p></th>
  <th><p><br/>4</p></th>
  <th><p><br/>5</p></th>
  <th><p><br/>6</p></th>
  <th><p><br/>7</p></th>
  <th><p><br/>8</p></th>
  <th><p><br/>9</p></th>
  <th><p>2<br/>0</p></th>
  <th><p><br/>1</p></th>
  <th><p><br/>2</p></th>
  <th><p><br/>3</p></th>
  <th><p><br/>4</p></th>
  <th><p><br/>5</p></th>
  <th><p><br/>6</p></th>
  <th><p><br/>7</p></th>
  <th><p><br/>8</p></th>
  <th><p><br/>9</p></th>
  <th><p>3<br/>0</p></th>
  <th><p><br/>1</p></th>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">Req_Func</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">Reserved1</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">dwRequestID</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">lpContext</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">hLine</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">dwAddressID</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">hCall</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">lpParamsContext</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">lpParams</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">dwSize</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">Reserved2</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">Reserved3</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">Reserved4</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">Reserved5</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">Reserved6</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">VarData
  (variable)</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">...</p>
  </td>
 </tr>
</tbody></table><p><b>Req_Func (4 bytes): </b>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.</p><dl>
<dd>
<p><b>Return Values</b></p>
</dd>
<dd>
<p>On completion of <a href="c28c36d0-579b-4e20-a100-f4e71012d5f8" data-linktype="relative-path">ClientRequest</a>, 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 <a href="e0e8af90-24f1-4dbc-8d4e-01b8e4e7cb53" data-linktype="relative-path">LINEERR_Constants</a>
value indicates synchronous failure.</p>
</dd>
<dd>
<p>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 <a href="8f5bc349-fd55-46f2-b0bc-dc9f757317a9" data-linktype="relative-path">LINE_REPLY</a> 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:</p>
</dd>
<dd>
<table><thead>
  <tr>
   <th>
   <p>Name</p>
   </th>
   <th>
   <p>Value</p>
   </th>
  </tr>
 </thead><tbody><tr>
  <td>
  <p>LINEERR_INVALLINEHANDLE</p>
  </td>
  <td>
  <p>0x8000002B</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_OPERATIONUNAVAIL</p>
  </td>
  <td>
  <p>0x80000049</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALADDRESSID</p>
  </td>
  <td>
  <p>0x80000011</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_OPERATIONFAILED</p>
  </td>
  <td>
  <p>0x80000048</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_NOMEM</p>
  </td>
  <td>
  <p>0x80000044</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_RESOURCEUNAVAIL</p>
  </td>
  <td>
  <p>0x8000004B</p>
  </td>
 </tr></tbody></table>
</dd></dl><p><b>Reserved1 (4 bytes): </b>An unsigned 32-bit
integer. MUST be set to zero when sent and MUST be ignored on receipt. </p><p><b>dwRequestID (4 bytes): </b>An unsigned 32-bit
integer. The identifier of the asynchronous request.</p><p><b>lpContext (4 bytes): </b>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.</p><p><b>hLine (4 bytes): </b>An <a href="9a80ee5c-cf55-4a86-bd67-173059d6ff3c" data-linktype="relative-path">HLINE</a>. The handle to a
line device. This field MUST have been obtained by sending the <a href="2759c744-e040-4c5d-b4b5-215d391f0490" data-linktype="relative-path">Open</a> packet. This
parameter is required.</p><p><b>dwAddressID (4 bytes): </b>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 <a href="f236ea7a-c8a2-4681-b87c-9f0e07a01dc6" data-linktype="relative-path">LINEDEVCAPS</a>obtained
by sending a <a href="ee317c21-100e-48a3-bcce-e9991efff889" data-linktype="relative-path">GetDevCaps</a>packet
to the remote server.</p><p><b>hCall (4 bytes): </b>An <a href="7f4089a0-7432-4ef0-8eeb-5aafe407c07e" data-linktype="relative-path">HCALL</a>. 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 <a href="c9acdfde-22de-43ff-b491-23a9ed72fb31" data-linktype="relative-path">MakeCall</a>
packet. The call state of hCall is device specific.</p><p><b>lpParamsContext (4 bytes): </b>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.</p><p><b>lpParams (4 bytes): </b>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.</p><p><b>dwSize (4 bytes): </b>An unsigned 32-bit integer.
The size, in bytes, of the parameter block that is indicated in the lpParams
field.</p><p><b>Reserved2 (4 bytes): </b>An unsigned 32-bit
integer. This field is used for padding and MUST be ignored on receipt. It can
be any value.</p><p><b>Reserved3 (4 bytes): </b>An unsigned 32-bit
integer. This field is used for padding and MUST be ignored on receipt. It can
be any value.</p><p><b>Reserved4 (4 bytes): </b>An unsigned 32-bit
integer. This field is used for padding and MUST be ignored on receipt. It can
be any value.</p><p><b>Reserved5 (4 bytes): </b>An unsigned 32-bit
integer. This field is used for padding and MUST be ignored on receipt. It can
be any value.</p><p><b>Reserved6 (4 bytes): </b>An unsigned 32-bit
integer. This field is used for padding and MUST be ignored on receipt. It can
be any value.</p><p><b>VarData (variable): </b>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.</p><dl>
<dd>
<p>The contents of this field MUST be DWORD-aligned, as
specified in <a href="../ms-dtyp/cca27429-5689-4a16-b2b4-9325d93e4ba2" data-linktype="relative-path">[MS-DTYP]</a>
section <a href="../ms-dtyp/262627d8-3418-4627-9218-4ffe110850b2" data-linktype="relative-path">2.2.9</a>.</p>
</dd></dl></div>