<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F" xml:lang="en"><title>Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The SIP Client API manages the multimedia sessions, subscribes to events,

and sends SIP messages. It also provides access to the basic services of the

SIP stack such as: </p>

<ul>

<li id="GUID-E9BF6031-1DAF-5238-A306-C44F0F91682D"><p>Sending and receiving

of SIP messages </p> </li>

<li id="GUID-C6A3FA97-1F09-587E-9504-9685D8306B04"><p>Creating registrations </p> </li>

<li id="GUID-A02F02C7-A903-53E0-A64E-F0B62C93A90F"><p>Forming and tearing

down dialogs initiated by INVITE, REFER and SUBSCRIBE requests </p> </li>

</ul>

<section id="GUID-8D3D5FB3-6037-5956-B3F0-DB14BD1BB17B"><title>Architectural

relationships</title> <p>The SIP Client API uses the client-server mechanism

to interact with the SIP stack. This means more than one client can use the

SIP stack at the same time. The calls to the SIP Client API are synchronous.

The SIP Client API implements a set of callback functions to pass the events

back to the application. </p> <p><b>Capability information</b> </p> <p>The

following table describes the capabilities required to use the SIP Client

API and the conditions in which they are required: </p> <table id="GUID-B3DCF31A-C6D5-58B9-87FA-B2CD3E0ABA1F">

<tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

<thead>

<row>

<entry>Capability </entry>

<entry>Reason needed </entry>

</row>

</thead>

<tbody>

<row>

<entry><p>NetworkServices </p> </entry>

<entry><p>to send or receive SIP messages </p> </entry>

</row>

<row>

<entry><p>WriteDeviceData </p> </entry>

<entry><p>to create an instance of the <xref href="GUID-AFB2603A-8A35-3E70-8EC2-229C9726F00B.dita"><apiname>CSIP</apiname></xref> class </p> </entry>

</row>

<row>

<entry><p>NetworkControl </p> <p>Location </p> <p>ReadDeviceData </p> </entry>

<entry><p>to use the function <codeph>CSIPConnection::SetOptL()</codeph>  </p> </entry>

</row>

</tbody>

</tgroup>

</table> <p><b>Extending the API</b> </p> <p>SIP Client API cannot be extended. </p> </section>

<section id="GUID-E055BF09-9605-57E6-9502-CB3F4CAC29B8"><title>SIP Client

API class structure</title> <ul>

<li id="GUID-3E500E7D-ECB9-50F8-B996-A212EE294E68"><p> <xref href="GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F.dita#GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F/GUID-581B8017-EAA0-59CB-A9CB-490370E0CEC9"> CSIP, MSIPObserver, CSIPConnection and MSIPConnectionObserver</xref>  </p> </li>

<li id="GUID-461F8201-ED85-582A-945C-7471F9BF27AA"><p> <xref href="GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F.dita#GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F/GUID-0E726099-31C4-5DD4-9AEA-67765589F462">Registration services</xref>  </p> </li>

<li id="GUID-F69AEAB7-0E13-5673-B696-843957CC4C72"><p> <xref href="GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F.dita#GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F/GUID-80CE8929-9DFD-5DCA-A929-662BD996223B"> SIP dialog associations</xref>  </p> </li>

<li id="GUID-BFE257A7-EF1A-58BF-A047-00E0B11B1FD3"><p> <xref href="GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F.dita#GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F/GUID-B0D208E4-D1F9-5C5F-B937-11118E778074">Requests sent to, and received from, the network</xref>  </p> </li>

<li id="GUID-D0AC4583-B181-501C-A97A-63F094AD4046"><p> <xref href="GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F.dita#GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F/GUID-0427709F-CD4B-5363-9377-10402B8A5819">SIP message related classes</xref>  </p> </li>

<li id="GUID-31ED307B-2285-5DE0-A83B-D0CB7A8C585D"><p> <xref href="GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F.dita#GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F/GUID-4E4FAFCA-0BF6-510C-B8E3-28A83936A154">Automatically refreshing a SIP request</xref>  </p> </li>

<li id="GUID-B6E46736-A250-5064-B4F8-595A20025478"><p> <xref href="GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F.dita#GUID-A29FD82C-B3CC-5862-8DAB-1398A61D8B1F/GUID-B71BC486-18C2-5E71-965E-0881FBA9CE85">Managing HTTP digest security settings</xref>  </p> </li>

</ul> <p id="GUID-581B8017-EAA0-59CB-A9CB-490370E0CEC9"><b> CSIP, MSIPObserver,

CSIPConnection and MSIPConnectionObserver </b> </p> <fig id="GUID-0834012C-083F-5FA0-B29D-E3E852165528">

<image href="GUID-4381EA7F-BE75-5B43-BE97-C97D71D04377_d0e312757_href.png" placement="inline"/>

</fig> <p>An application creates a single instance of the <xref href="GUID-AFB2603A-8A35-3E70-8EC2-229C9726F00B.dita"><apiname>CSIP</apiname></xref> class,

and implements the callback functions defined by <xref href="GUID-C6FF4A83-0097-3A82-B4ED-802E1FEA05D1.dita"><apiname>MSIPObserver</apiname></xref>.

The <codeph>CSIP</codeph> uses the <codeph>MSIPObserver</codeph> functions.

The <xref href="GUID-AFB2603A-8A35-3E70-8EC2-229C9726F00B.dita"><apiname>CSIP</apiname></xref> class asks the supported security mechanisms and

determines whether a <xref href="GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94.dita"><apiname>CSIPConnection</apiname></xref> object exists for a

given IAP. </p> <p>The <xref href="GUID-AFB2603A-8A35-3E70-8EC2-229C9726F00B.dita"><apiname>CSIP</apiname></xref> object creates an instance

of <xref href="GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94.dita"><apiname>CSIPConnection</apiname></xref> that allows you to send standalone SIP

requests and ask for the state of the network connection. Responses are received

through the <xref href="GUID-B889A3FD-3B14-3785-90AE-3546F0C9A5D4.dita"><apiname>MSIPConnectionObserver</apiname></xref> interface that defines

a set of callback functions that an application must implement. </p> <p>An

application can have many <xref href="GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94.dita"><apiname>CSIPConnection</apiname></xref> objects, but each

of them must have a different IAP. </p> <p id="GUID-0E726099-31C4-5DD4-9AEA-67765589F462"><b>Registration

services</b> </p> <fig id="GUID-63E38B2E-975E-554C-8EDC-65B8BBA86838">

<image href="GUID-E4543D60-A9D0-5121-9540-993BB15D3275_d0e312814_href.png" placement="inline"/>

</fig> <p>An existing <xref href="GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94.dita"><apiname>CSIPConnection</apiname></xref> is required to create

an instance of <codeph>CSIPRegistrationBinding</codeph>. The <xref href="GUID-48AA01D5-CE7B-3C22-B2E0-529261121EC4.dita"><apiname>CSIPRegistrationBinding</apiname></xref> class

provides services for registration, updating the registration, and deregistration.

This class also provides instructions to the SIP stack to automatically refresh

the registration, and to query and set the outbound proxy used by the registration. </p> <p id="GUID-80CE8929-9DFD-5DCA-A929-662BD996223B"><b> SIP dialog

associations</b> </p> <fig id="GUID-4870BE80-44B6-50F0-B77E-73FEAD136304">

<image href="GUID-17D1489B-F7F7-5CA7-9F81-850AA9ACEFEB_d0e312839_href.png" placement="inline"/>

</fig> <p> <xref href="GUID-9841AF1A-B8CF-3BA1-8445-93064549AE8C.dita"><apiname>CSIPDialogAssocBase</apiname></xref> is the base class for SIP

dialog associations, such as <xref href="GUID-B4A2FBBD-2B5F-3E64-800D-C4E9203679A8.dita"><apiname>CSIPInviteDialogAssoc</apiname></xref>, <xref href="GUID-9539CAEE-28AE-3134-8415-EEBCBCDA4D18.dita"><apiname>CSIPSubscribeDialogAssoc</apiname></xref>, <xref href="GUID-2E7EF887-ED59-3E8A-B9A2-686DF879A16C.dita"><apiname>CSIPReferDialogAssoc</apiname></xref> and <xref href="GUID-72F96612-A95C-3066-BFF0-2E288C945A2A.dita"><apiname>CSIPNotifyDialogAssoc</apiname></xref>. The <xref href="GUID-9841AF1A-B8CF-3BA1-8445-93064549AE8C.dita"><apiname>CSIPDialogAssocBase</apiname></xref> class

is used to obtain the associated SIP dialog, for the associated <xref href="GUID-382BC1BE-3CF3-3E81-B1FF-341EEF2B67EA.dita"><apiname>CSIPDialog</apiname></xref> instance,

and for sending a non-target Refresh request within the dialog. </p> <p> <b> Note: </b> The

SIP Client API creates the <xref href="GUID-382BC1BE-3CF3-3E81-B1FF-341EEF2B67EA.dita"><apiname>CSIPDialog</apiname></xref> instance, it cannot

be created by the application. </p> <p>If any of the <xref href="GUID-B4A2FBBD-2B5F-3E64-800D-C4E9203679A8.dita"><apiname>CSIPInviteDialogAssoc</apiname></xref>, <xref href="GUID-9539CAEE-28AE-3134-8415-EEBCBCDA4D18.dita"><apiname>CSIPSubscribeDialogAssoc</apiname></xref>, <xref href="GUID-2E7EF887-ED59-3E8A-B9A2-686DF879A16C.dita"><apiname>CSIPReferDialogAssoc</apiname></xref> and <xref href="GUID-72F96612-A95C-3066-BFF0-2E288C945A2A.dita"><apiname>CSIPNotifyDialogAssoc</apiname></xref> objects

are associated, they are bound to an existing <xref href="GUID-382BC1BE-3CF3-3E81-B1FF-341EEF2B67EA.dita"><apiname>CSIPDialog</apiname></xref> object,

or they can be used to create a new <codeph>CSIPDialog</codeph> object. </p> <p> <b>Note:</b>  </p> <ul>

<li id="GUID-6A085F6F-C243-53AD-B33C-F37D14DFE0A4"><p> <xref href="GUID-B4A2FBBD-2B5F-3E64-800D-C4E9203679A8.dita"><apiname>CSIPInviteDialogAssoc</apiname></xref> allows

an application to initiate a dialog and to send <codeph>INVITE</codeph>,,<codeph>PRACK</codeph>,,<codeph>ACK</codeph>, <codeph>UPDATE,</codeph> and <codeph>BYE</codeph> requests related to the dialog. </p> </li>

<li id="GUID-19C504F0-EAD5-524A-82E9-2D15BFA2A6D2"><p> <xref href="GUID-9539CAEE-28AE-3134-8415-EEBCBCDA4D18.dita"><apiname>CSIPSubscribeDialogAssoc</apiname></xref> allows

an application to subscribe to different events by sending SUBSCRIBE and UNSUBSCRIBE

requests. It also orders the SIP stack to automatically refresh the SUBSCRIBE

request. </p> </li>

<li id="GUID-C47B74D8-2251-5FCC-A356-1364EB61CF05"><p> <xref href="GUID-2E7EF887-ED59-3E8A-B9A2-686DF879A16C.dita"><apiname>CSIPReferDialogAssoc</apiname></xref> allows

an application to define and send REFER requests. </p> </li>

<li id="GUID-18AD2000-2A37-5CD9-8118-8B3322211D28"><p> <xref href="GUID-72F96612-A95C-3066-BFF0-2E288C945A2A.dita"><apiname> CSIPNotifyDialogAssoc</apiname></xref> allows

an application to define and send NOTIFY requests. </p> </li>

</ul> <p id="GUID-B0D208E4-D1F9-5C5F-B937-11118E778074"><b>Sent and received

network requests</b> </p> <fig id="GUID-2E0C9020-1863-5644-BF7E-62B4DB9104D2">

<image href="GUID-F5A82F61-B93A-5652-93A4-B9CE877B4D4A_d0e312976_href.png" placement="inline"/>

</fig> <p>When a SIP request is sent to the network, the SIP Client API implementation

creates a <xref href="GUID-059F9C3A-EA04-3295-912F-50444F073CE7.dita"><apiname>CSIPClientTransaction</apiname></xref> object and returns it to

the application. A <codeph>CSIPClientTransaction</codeph> object represents

the SIP transaction and consists of the SIP request and the SIP response.

After receiving a response, the application gets <xref href="GUID-13F32052-70BE-3B4D-9F8B-DF2DABB896B0.dita"><apiname>CSIPResponseElements</apiname></xref> from

the <codeph>CSIPClientTransaction</codeph> object. <b>Note:</b> Some client

transactions can also be cancelled or refreshed. </p> <p>When a SIP request

is received from the network, it is passed to the application as a <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref> object.

The application gets <xref href="GUID-19FB031A-CFA7-3C67-A627-CFF501060AA5.dita"><apiname>CSIPRequestElements</apiname></xref> from the <codeph>CSIPServerTransaction</codeph> object.

A <codeph>CSIPRequestElements</codeph> object describes the kind of SIP request

received. After the application determines the type of response to send, it

uses the <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref> to send the responses. </p> <p> <xref href="GUID-93256B64-49C9-37F1-9A4E-72C521759749.dita"><apiname>CSIPTransactionBase</apiname></xref> is

the base class for <xref href="GUID-059F9C3A-EA04-3295-912F-50444F073CE7.dita"><apiname>CSIPClientTransaction</apiname></xref> and <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref>.

It provides the functions to obtain the current state of the transaction and

the transaction type. Some operations are only allowed when the transaction

is in a certain state. <b>Note:</b> The SIP Client API creates instances of <xref href="GUID-059F9C3A-EA04-3295-912F-50444F073CE7.dita"><apiname>CSIPClientTransaction</apiname></xref> and <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref> and they cannot be created by the application. </p> <p id="GUID-0427709F-CD4B-5363-9377-10402B8A5819"><b>SIP

message related classes</b> </p> <fig id="GUID-B99CF040-E91F-5281-8AAC-2151049C0EA8">

<image href="GUID-6290D35A-7A41-5B9E-882A-E14F6D165ED7_d0e313053_href.png" placement="inline"/>

</fig> <p>When a SIP request is sent to the network, the SIP Client API implementation

creates a <xref href="GUID-059F9C3A-EA04-3295-912F-50444F073CE7.dita"><apiname>CSIPClientTransaction</apiname></xref> object and returns it to

the application. A <codeph>CSIPClientTransaction</codeph> object represents

the SIP transaction and consists of the SIP request and the SIP response.

After receiving a response the application gets <xref href="GUID-13F32052-70BE-3B4D-9F8B-DF2DABB896B0.dita"><apiname>CSIPResponseElements</apiname></xref> from

the <codeph>CSIPClientTransaction</codeph> object. <b>Note:</b> Some client

transactions can be cancelled or refreshed. </p> <p>When a SIP request is

received from the network, it is passed to the application as a <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref> object.

The application gets <xref href="GUID-19FB031A-CFA7-3C67-A627-CFF501060AA5.dita"><apiname>CSIPRequestElements</apiname></xref> from the <codeph>CSIPServerTransaction</codeph> object.

A <codeph>CSIPRequestElements</codeph> object describes the type of SIP request

received. After the application determines the type of response to send, it

uses the <codeph>CSIPServerTransaction</codeph> to send the responses. </p> <p> <xref href="GUID-93256B64-49C9-37F1-9A4E-72C521759749.dita"><apiname>CSIPTransactionBase</apiname></xref> is

the base class for <xref href="GUID-059F9C3A-EA04-3295-912F-50444F073CE7.dita"><apiname>CSIPClientTransaction</apiname></xref> and <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref>.

It provides functions to obtain the current state of the transaction and the

transaction type. Some operations are only allowed when the transaction is

in a certain state. <b>Note:</b> The SIP Client API creates instances of <xref href="GUID-059F9C3A-EA04-3295-912F-50444F073CE7.dita"><apiname>CSIPClientTransaction</apiname></xref> and <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref> and they cannot be created by the application. </p> <p id="GUID-4E4FAFCA-0BF6-510C-B8E3-28A83936A154"><b> Automatically

refreshing a SIP request</b> </p> <fig id="GUID-49ACB697-512C-5FCF-AD48-20D6AAB0FEFC">

<image href="GUID-6B9E5B8D-E2F7-5972-ABFB-49F7F466EBBD_d0e313129_href.png" placement="inline"/>

</fig> <p>The SIP stack automatically refreshes a SIP request using the <xref href="GUID-3C166C85-6E17-323B-9CD3-B3E2836DC1C3.dita"><apiname>CSIPRefresh</apiname></xref> object. <codeph>REGISTER</codeph>, <codeph>SUBSCRIBE</codeph> and a request outside the dialog are refreshed. After

sending a refresh request, the application queries the state of the refresh

from <codeph>CSIPRefresh</codeph>. </p> <p> <codeph>CSIPRefresh</codeph> provides

functions for updating and terminating the refresh, for requests outside the

dialog. The <xref href="GUID-48AA01D5-CE7B-3C22-B2E0-529261121EC4.dita"><apiname>CSIPRegistrationBinding</apiname></xref> and <xref href="GUID-9539CAEE-28AE-3134-8415-EEBCBCDA4D18.dita"><apiname>CSIPSubscribeDialogAssoc</apiname></xref> classes

are used to update and terminate a refreshed <codeph>REGISTER</codeph> or <codeph>SUBSCRIBE</codeph>. </p> <p id="GUID-B71BC486-18C2-5E71-965E-0881FBA9CE85"><b> Managing HTTP digest security

settings </b> </p> <fig id="GUID-7C296C1B-67E3-569F-A5E9-92A4F7922088">

<image href="GUID-1704898B-7836-53C2-8743-F733836EDE7B_d0e313175_href.png" placement="inline"/>

</fig> <p>An application must create an instance of the <xref href="GUID-AFB2603A-8A35-3E70-8EC2-229C9726F00B.dita"><apiname>CSIP</apiname></xref> class

to use <codeph>CSIPHttpDigest</codeph>. The <xref href="GUID-F9FBAFBE-A895-3FD3-A526-604A6C9E035D.dita"><apiname>CSIPHttpDigest</apiname></xref> class

manages HTTP digest security settings and contains only static functions. </p> </section>

<section id="GUID-4195FAF9-D0D7-5046-BD62-9A314791BEFE"><title>Memory used</title> <p>After

the <xref href="GUID-AFB2603A-8A35-3E70-8EC2-229C9726F00B.dita"><apiname>CSIP</apiname></xref> and <xref href="GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94.dita"><apiname>CSIPConnection</apiname></xref> objects

are created, most of the memory consumed is by <xref href="GUID-77CFD812-7238-3B84-80FF-475BD73C3506.dita"><apiname>CSIPMessageElements</apiname></xref>, <xref href="GUID-19FB031A-CFA7-3C67-A627-CFF501060AA5.dita"><apiname>CSIPRequestElements</apiname></xref> and <xref href="GUID-13F32052-70BE-3B4D-9F8B-DF2DABB896B0.dita"><apiname>CSIPResponseElements</apiname></xref> classes. <xref href="GUID-93256B64-49C9-37F1-9A4E-72C521759749.dita"><apiname>CSIPTransactionBase</apiname></xref> holds the most recent SIP

response in a <xref href="GUID-13F32052-70BE-3B4D-9F8B-DF2DABB896B0.dita"><apiname>CSIPResponseElements</apiname></xref> object. When another

response is received, the previous <xref href="GUID-13F32052-70BE-3B4D-9F8B-DF2DABB896B0.dita"><apiname>CSIPResponseElements</apiname></xref> object

is deleted and a new one is created. </p> <p> <xref href="GUID-059F9C3A-EA04-3295-912F-50444F073CE7.dita"><apiname>CSIPClientTransaction</apiname></xref> contains

a <xref href="GUID-19FB031A-CFA7-3C67-A627-CFF501060AA5.dita"><apiname>CSIPRequestElements</apiname></xref> object until the SIP request is transferred

to the server side of the SIP stack. <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref> contains

the SIP request as <xref href="GUID-19FB031A-CFA7-3C67-A627-CFF501060AA5.dita"><apiname>CSIPRequestElements</apiname></xref>. The application

owns the <xref href="GUID-059F9C3A-EA04-3295-912F-50444F073CE7.dita"><apiname>CSIPClientTransaction</apiname></xref> and <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref> objects.

When the transaction terminates, the application deletes these objects to

conserve memory. </p> <p>A non-<codeph>INVITE</codeph>  <codeph>CSIPClientTransaction</codeph> is

deleted when it has received a final response or when the <codeph>ErrorOccured()</codeph> callback

is called. A non-<codeph>INVITE</codeph> <codeph>CSIPServerTransaction</codeph> is

deleted after the application sends a final response. </p> <p>The <codeph>INVITE</codeph> related

transactions are deleted if the <codeph>ErrorOccured()</codeph> callback function

is called. These transactions behave differently because of the presence of

an <codeph>ACK</codeph>. </p> <p>When the application sends a 2xx response

to an <codeph>INVITE</codeph> related <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref>,

it enters the <xref href="GUID-93256B64-49C9-37F1-9A4E-72C521759749.dita#GUID-93256B64-49C9-37F1-9A4E-72C521759749/GUID-DF7E4DCE-1F6D-3F2A-A638-5516A733AA9D"><apiname>CSIPTransactionBase::ETerminated</apiname></xref> state and

it is deleted at this point. A new <xref href="GUID-7E54C95E-5155-30B1-8169-A59778774403.dita"><apiname>CSIPServerTransaction</apiname></xref> object

receives the ACK. </p> <p>When the application sends an <codeph>INVITE</codeph> request

and the <codeph>CSIPClientTransaction</codeph> receives a 2xx response, the

transaction enters the <codeph>CSIPTransactionBase::ETerminated</codeph> state.

The associated <codeph>CSIPClientTransaction</codeph> must not be deleted

as it is required to send the <codeph>ACK</codeph> and also to receive the <xref href="GUID-B889A3FD-3B14-3785-90AE-3546F0C9A5D4.dita#GUID-B889A3FD-3B14-3785-90AE-3546F0C9A5D4/GUID-2E76BDA0-CE87-3538-A791-963A90230FD4"><apiname>MSIPConnectionObserver::InviteCompleted()</apiname></xref> callback.

An <codeph>INVITE</codeph> related <codeph>CSIPClientTransaction</codeph> must

be deleted only after a <codeph>MSIPConnectionObserver::InviteCompleted</codeph> or <xref href="GUID-D14D6845-1C5E-3C15-8310-574A2A8C6C95.dita#GUID-D14D6845-1C5E-3C15-8310-574A2A8C6C95/GUID-DED382FB-A6D5-37D7-B8E4-05262F690068"><apiname>MSIPConnectionObserver

::ErrorOccured</apiname></xref> event is received, or if the state of the associated <xref href="GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94.dita"><apiname>CSIPConnection</apiname></xref> goes

to <xref href="GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94.dita#GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94/GUID-68DD22DC-67E4-387B-BBE9-B9B96D9C9016"><apiname>CSIPConnection::EInactive</apiname></xref> or <xref href="GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94.dita#GUID-2A070F4D-A35B-3505-BE86-E6C7A2F27B94/GUID-5963A947-BD5C-3B34-9D10-2CB5DC413774"><apiname>CSIPConnection::EUnavailable</apiname></xref>. </p> </section>

</conbody></concept>