Calls
Calls are represented by pj::Call
class.
Subclassing the Call class
To use the Call
class, application SHOULD subclass it, such as:
class MyCall : public Call
{
public:
MyCall(Account &acc, int call_id = PJSUA_INVALID_ID)
: Call(acc, call_id)
{ }
~MyCall()
{ }
// Notification when call's state has changed.
virtual void onCallState(OnCallStateParam &prm);
// Notification when call's media state has changed.
virtual void onCallMediaState(OnCallMediaStateParam &prm);
};
Application implement Call’s callbacks to process events related to the call, such as
pj::Call::onCallState()
, and many more. See pj::Call
class
for more info.
Making outgoing calls
Make outgoing call is by invoking pj::Call::makeCall()
with the destination URI
string (something like "sip:alice@example.com"
). The URI can also be enclosed in name-addr
form ([ display-name ] <SIP/SIPS URI>
) (such as "Alice <sip:alice@example.com;transport=tcp>"
).
Note that an account instance is required to create a call instance:
Call *call = new MyCall(*acc);
CallOpParam prm(true); // Use default call settings
try {
call->makeCall(dest_uri, prm);
} catch(Error& err) {
cout << err.info() << endl;
}
Receiving Incoming Calls
Incoming calls are reported as pj::Account::onIncomingCall()
callback. Note that
this is the callback of the pj::Account
class (not pj::Call
). You must derive a class from the
pj::Account
class to handle incoming calls.
Below is a sample code of the callback implementation:
void MyAccount::onIncomingCall(OnIncomingCallParam &iprm)
{
Call *call = new MyCall(*this, iprm.callId);
CallOpParam prm;
prm.statusCode = PJSIP_SC_OK;
call->answer(prm);
}
For incoming calls, the call instance is created in the callback function as shown above. Application should make sure to store the call instance during the lifetime of the call (that is until the call is disconnected (see Call Disconnection below)).
Call Properties
All call properties such as state, media state, remote peer information, etc. are stored in
pj::CallInfo
class, which can be retrieved from the call object with using
pj::Call::getInfo()
method.
Call Disconnection
Call disconnection event is a special event since once the callback that reports this event returns, the call is no longer valid and any operations invoked to the call object will raise error exception. Thus, it is recommended to delete the call object inside the callback.
The call disconnection is reported in pj::Call::onCallState()
callback. Below is
a sample implementation:
void MyCall::onCallState(OnCallStateParam &prm)
{
CallInfo ci = getInfo();
if (ci.state == PJSIP_INV_STATE_DISCONNECTED) {
/* Delete the call */
delete this;
}
}
Working with Call’s Audio Media
Application can only operate the call’s audio media when the call’s audio media state is ready (or active). Usually this happens once the call has been established, although media can active before that (it is called early media), and established call can have no media (such as when it is being put on-hold).
The changes to the call’s media state is reported in pj::Call::onCallMediaState()
callback.
Only when the call’s audio media state is ready (or active) the function pj::Call::getAudioMedia()
will return a valid audio media.
Below is a sample code to connect the call to the sound device when the media is active:
void MyCall::onCallMediaState(OnCallMediaStateParam &prm)
{
CallInfo ci = getInfo();
for (unsigned i = 0; i < ci.media.size(); i++) {
if (ci.media[i].type==PJMEDIA_TYPE_AUDIO) {
try {
AudioMedia aud_med = getAudioMedia(i);
// Connect the call audio media to sound device
AudDevManager& mgr = Endpoint::instance().audDevManager();
aud_med.startTransmit(mgr.getPlaybackDevMedia());
mgr.getCaptureDevMedia().startTransmit(aud_med);
}
catch(const Error &e) {
// Handle invalid or not audio media error here
}
}
}
}
When the audio media becomes inactive (for example when the call is put on hold), there is no need to stop the call’s audio media transmission since they will be removed automatically from the conference bridge, and this will automatically remove all connections to/from the call.
Call Operations
Call have many other operations, such as hanging up, putting the call on hold, sending re-INVITE, etc.
See pj::Call
reference for more info.
Instant Messaging(IM)
Note
Usually it is more appropriate to do instant messaging outside the context of a
call. Application can send IM and typing indication outside a call by using
pj::Buddy::sendInstantMessage()
and pj::Buddy::sendTypingIndication()
.
More will be explained in the next section.
Application can send IM within a call using pj::Call::sendInstantMessage()
. The transmission status
of outgoing instant messages is reported in pj::Call::onInstantMessageStatus()
callback.
In addition, you can also send typing indication using
pj::Call::sendTypingIndication()
.
Incoming IM and typing indication received within a call will be reported in
pj::Call::onInstantMessage()
and pj::Call::onTypingIndication()
callbacks.
While it is recommended to send IM outside call context, application should handle incoming IM inside call context for robustness.