Creating A Conference; Joining A Conference; Terminating A Conference - AudioCodes Mediant 600 User Manual

33.1.2 Creating a Conference

The device creates a conference call when the first user joins the conference. To create a
conference, the Application Server sends a regular SIP INVITE message to the device.
The User Part of that Request-URI includes both the Conference Service Identifier
(indicating that the requested Media Service is a Conference) and a Unique Conference
Identifier (identifying a specific instance of a conference).
INVITE sip: conf100@audiocodes.com SIP/2.0
By default, a request to create a conference reserves three resources on the device. It is
possible to reserve a larger number of resources in advance by adding the number of
required participants to the User Part of the Request-URI. For example, '6conf100'
reserves six resources for the duration of the conference. If the device can allocate the
requested number of resources, it responds with a 200 OK.
The Conference Service Identifier can be configured using the 'Conference ID' parameter
(ConferenceID), located in the IP Media Settings page (Configuration tab > VoIP menu >
IP Media > IP Media Settings). By default, it is set to 'conf'.

33.1.3 Joining a Conference

To join an existing conference, the Application Server sends a SIP INVITE message with
the same Request-URI as the one that created the conference. Each conference
participant can use a different coder negotiated with the device using usual SIP
negotiation.
If more than the initially requested number of participants try to join the conference (i.e.,
four resources were reserved and a fifth INVITE is received) and the device has an
available resource, the request is granted.
If an INVITE to join an existing conference is received with a request to reserve a larger
number of participants than initially requested, it is granted if the device has available
resources. A request for a smaller number of participants is not granted as this may create
a situation where existing legs would need to be disconnected.
The maximal number of participants in a single conference is 60. The maximal number of
participants that actually participate in the mix at a given time is three (the loudest legs).
The Application Server can place a participant on Hold/Un-hold by sending the appropriate
SIP Re-INVITE on that participant dialog.

33.1.4 Terminating a Conference

The device never disconnects an existing conference leg. If a BYE is received on an
existing leg, it is disconnected, but the resource is still saved if the same leg (or a different
one) wants to re-join the conference. This logic occurs only for the initial number of
reserved legs.
For example:
1. INVITE reserves three legs.
2. A, B, and C join the conference.
3. A disconnects.
4. A joins (guaranteed).
5. D joins.
6. A disconnects.
7. A joins (not guaranteed).
Sending a BYE request to the device terminates the participant's SIP session and removes
it from the conference. The final BYE from the last participant ends the conference and
releases all conference resources.
User's Manual 454
Mediant 600 & Mediant 1000
Document #: LTRT-83313