<div class="content"><p>The PrepareAddToConference 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>.
Sending this packet prepares an existing conference call for the addition of
another party. It creates a new, temporary consultation call. The new
consultation call can be subsequently added to the conference call.</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">hConfCall</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">lphConsultCallContext</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">lpCallParams</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">dwAsciiCallParamsCodePage</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">Reserved7</p>
  </td>
 </tr>
 <tr>
  <td colspan="32">
  <p align="center">Reserved8</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 57.</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_BEARERMODEUNAVAIL</p>
  </td>
  <td>
  <p>0x80000003</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALLINESTATE</p>
  </td>
  <td>
  <p>0x8000002C</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_CALLUNAVAIL</p>
  </td>
  <td>
  <p>0x80000005</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALMEDIAMODE</p>
  </td>
  <td>
  <p>0x8000002F</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_CONFERENCEFULL</p>
  </td>
  <td>
  <p>0x80000007</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALRATE</p>
  </td>
  <td>
  <p>0x80000037</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INUSE</p>
  </td>
  <td>
  <p>0x8000000F</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_NOMEM</p>
  </td>
  <td>
  <p>0x80000044</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALADDRESSMODE</p>
  </td>
  <td>
  <p>0x80000012</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_OPERATIONUNAVAIL</p>
  </td>
  <td>
  <p>0x80000049</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALBEARERMODE</p>
  </td>
  <td>
  <p>0x80000016</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_OPERATIONFAILED</p>
  </td>
  <td>
  <p>0x80000048</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALCALLPARAMS</p>
  </td>
  <td>
  <p>0x80000019</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_RATEUNAVAIL</p>
  </td>
  <td>
  <p>0x8000004A</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALCALLSTATE</p>
  </td>
  <td>
  <p>0x8000001C</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_RESOURCEUNAVAIL</p>
  </td>
  <td>
  <p>0x8000004B</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_INVALCONFCALLHANDLE</p>
  </td>
  <td>
  <p>0x80000020</p>
  </td>
 </tr><tr>
  <td>
  <p>LINEERR_USERUSERINFOTOOBIG</p>
  </td>
  <td>
  <p>0x80000051</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>hConfCall (4 bytes): </b>An <a href="7f4089a0-7432-4ef0-8eeb-5aafe407c07e" data-linktype="relative-path">HCALL</a>. The handle to a
conference call. This field MUST have been obtained by sending the <a href="8182ee39-63db-4ce7-b4eb-f742cbf2eeef" data-linktype="relative-path">SetUpConference</a> packet.
The application MUST be an owner of this call. The call state of hConfCall MUST
be connected.</p><p><b>lphConsultCallContext (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>lpCallParams (4 bytes): </b>An unsigned 32-bit
integer. The offset, in bytes, in the VarData field of a <a href="c72ece07-095d-441a-93cd-660f09b7826f" data-linktype="relative-path">LINECALLPARAMS</a> packet that
contains call parameters to use when establishing the consultation call. If
this field is -1 (0xFFFFFFFF), no call parameters are sent.</p><p><b>dwAsciiCallParamsCodePage (4 bytes): </b>An
unsigned 32-bit integer. This MUST be set to TAPI_NO_DATA (0xFFFFFFFF).</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>Reserved7 (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>Reserved8 (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 LINECALLPARAMS
packet.</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>