wiki:Python_SIP/Calls

Version 1 (modified by bennylp, 11 years ago) (diff)

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Calls

Calls are represented by Call class.

Making Outgoing Calls

Making outgoing call is simple, just invoke make_call() method of the Account object. Assuming you have the account object as acc variable and destination URI string in dst_uri:

try:
    my_cb = MyCallCallback()
    call = acc.make_call(dst_uri, cb=my_cb)
except pjsua.Error, err:
    print 'Error making outgoing call:', err

The snippet above initiates outgoing call to dst_uri, install the callback to the call, and saves the call instance in call object. Subsequent operations to the call can use the method in the call instance, and events to the call will be reported to the callback.

More on the callback will be explained a bit later.

Receiving Incoming Calls

Incoming calls are reported as on_incoming_call() of the AccountCallback class. You must derive a class from the AccountCallback to handle incoming calls:

class MyAccountCallback(pjsua.AccountCallback):
    def __init__(self, account=None):
        pjsua.AccountCallback.__init__(self, account)

    def on_incoming_call(self, call):
        my_cb = MyCallCallback()
        call.set_callback(my_cb)

For incoming calls, the call instance is given in the callback parameter as shown above. We just need to install our callback to receive call events to the call.

Call Operations

Please see Call class documentation.

Handling Call Events

All call properties such as state, media state, remote peer information, etc. are stored as CallInfo class, which can be retrieved from the call object with using info() method of the call.

Handling Call Events

Events to the call will be reported to CallCallback instance that is installed to the call object. To handle these events, you must derive a class from CallCallback class and install the instance to the call object.

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Call disconnection event is a special event since once the callback that reports this event returns, the call is no longer valid and any operations invoked to the call object will raise error exception.

The call disconnection is reported in on_state() method of CallCallback and it can be detected as follows:

class MyCallCallback(pjsua.CallCallback):
    ...
    def on_state(self):
        if self.call.info().state == pjsua.CallState.DISCONNECTED:
            print 'This call has been disconnected'

Working with Call's Media

You can only operate with the call's media (e.g. connecting the call to the sound device in the conference bridge) when the call's media is ready (or active). The changes to the call's media state is reported in on_media_state() callback, and the media state itself is stored as the media_state member of CallInfo class.

The media state value can be one of the MediaState constant.

Below is a sample code to connect the call to the sound device when the call's media state is active:

class MyCallCallback(pjsua.CallCallback):
    ...
    # Notification when call's media state has changed.
    def on_media_state(self):
        if self.call.info().media_state == pj.MediaState.ACTIVE:
            # Connect the call to sound device
            call_slot = self.call.info().conf_slot
            pj.Lib.instance().conf_connect(call_slot, 0)
            pj.Lib.instance().conf_connect(0, call_slot)
            print "Media is now active"
        else:
            print "Media is inactive"

When the media_state has moved from active to non-active (for example when call is put on hold), there is no need to disconnect the call's connection in the bridge since the call's media will be removed automatically when it's no longer valid, and this will automatically remote all connections in the conference bridge to/from the call.