Howto12r1:Conferences, Resources and Licenses

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There are also other versions of this article available: Howto | Howto12r1 (this version) | Howto13r1 | Howto13r2 | Howto13r3

Applies To

This information applies to

all innovaphone devices supporting a CONF or SCNF interface and hence Conference Channels (as shown in the devices home-page).

More Information

Performing conferencing on a CONF or SCNF interface consumes both resources and licenses. Here is an overview of which and how much.


First let us have a look at the overall scheme:

Conferences, Ressources and Licenses - Scheme2.png

The CONF interface provides the mixing of 8KHz G711 PCM audio channels. The audio channel originates from a VoIP endpoint and a Coder channel from the DSP coder channel bank is required for processing of the audio from VoIP codec (e.g. G.711, G.722, OPUS) to PCM audio. An exception is made for software based conference interface SCNF on IPVA, where only G.711 endpoints are supported and no local DSP coder hardware channels are required.

A caller from a VoIP endpoint establishes a connection through the conferencing unit's VoIP interface. There are no license for such connections required, but the VoIP interface itself needs to register with the PBX and thus a Port license is required. Also, to connect the audio stream to the conferencing circuitry, one DSP coder channel and one conference channel is required per such call. As there are licenses required for use of a conference channel, both the (Channel) license and the DSP coder channel itself must be available (depending on the platform).

Conferences, Ressources and Licenses - Channel usage diagram.png

As a result, a caller from e.g. the ISDN needs an available B-channel on the ISDN interface. There are no licenses for B-channels required, but the ISDN interface itself must be licensed. In addition, a Conference Channel is required. There is no license required to use a Conference Channel, however, such channels are a limited resource (depending on the platform), so there must be one available.

The resources (and hence the licenses) are required on the device that provides the CONF interface. If you do not want to cannibalize your PSTN gateway ressources and run the risk of not being able to perform PSTN calls due to missing DSP coder channels consumed by conferencing calls, you can easily add an extra gateway with CONF support just for conferencing (the IP0010 or IP1060 may be a good choice, featuring 60 conferencing channels).


Channels License

  • Bound to hardware and can not be moved to other hardware
  • License type as listed in the and in the file license-.xml: Relay-Channels
  • Admin UI appearance: Gateway Channels
  • Order Number: 01-00500-004


An IPVA provides a software based conference interface only, that can connect VoIP endpoints with G711a/G711u codec support. The software based conferences are provided by the SCNF interfaces. For more information refer to Reference13r1:Concept Soft Conference.

Example Scenarios

Conference on Hardware Gateway with local ISDN

Let us assume we have a conference with one PSTN and 3 VoIP participants. In this case, we have

Caller DSP Coder Channel Conference Channel Channel License
1 PSTN 1 1 1
3 VoIP 3 3 3
Total 4 4 4

Looking at an IP411, it supports the following resources:

Conferences, Ressources and Licenses - example gateway channels IP411.png

We can see that our sample scenario will work on an IP411 (if the ISDN interface is licensed and 4 Channel licenses are available). However, keep in mind that DSP coder channels and licenses are used for straight gateway calls too. In our sample scenario, although we have 2 BRI with 4 B-channels, we cannot use 4 B channels, as we run out of DSP coder channels (as each call from an ISDN interface to a VoIP endpoint uses one DSP coder channel too).

Conference on IPVA with remote ISDN

In this example we assume one IPVA with Soft Conference channels serving conference room for two ISDN and two VoIP participants.

Devices used in this scenario:

  • The IPVA provides up to 60 conference channels with no need for local DSP coder channels, since only G.711 codec is supported.
  • A remote ISDN gateway will provide 2 ISDN interfaces channels with local DSP coder channels.

The usage of the channels and licenses is calculated as following

2 VoIP endpoints will require 2 Soft Conference Channels on IPVA + 2 PBX-Channel Licenses
2 ISDN endpoints will require 2 Soft Conference Channels on IPVA + 2 PBX-Channel Licenses + 2 Channel Licenses bound on remote ISDN Gateway

3PTY Conferencing

3-way conferencing is special as it is usually implemented internally in the innovaphone IP phones. That is, each user of an innovaphone IP phone (except the IP61) has internal conferencing ressources built-in to allow for a 3-way conference. No external CONF interface is needed.

However, on innovaphone DECT phones, no internal conferencing resource is present and hence no internal 3PTY is possible. The DECT system can thus be configured to use an external conferencing resource for 3PTY. In this case, the rules above apply.

Note: if you configure ITALY-PUBLIC dial tone on the phones, you will hear every 5 seconds a "bip" during the 3PTY conference. This has been added to be in line with the italian law regarding conference.

Multi-party Conferencing from myPBX V9 (deprecated)

V9 myPBX has a built-in interface to multi-party conferencing. Although myPBX hides all the details of allocating the conference resources from the user, it still uses the same mechanism. The rules outlined above apply thus. This mechanism is not available in later versions of myPBX.

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