Yes, absolutely it is much clearer.
You are right, we are registering the recorded phones in dependent mode with server media mode.
What we were missing is the actual implementation of the VUS. Now, we understand it.
But your explanation has raised a new question:
Using VUS in server media mode with CM 4.x and AES 4.1 enables this RTP forking, then what is new in CM 5.x?

Just to make sure we're absolutely clear, VUS really doesn't *enable* RTP forking, it allows your application to *utilize* RTP forking in a server media mode.

You've discovered that basic RTP forking functionality exists in CM 4.0. Unfortunately it is not officially supported until CM 5.0 because some important bug fixes and enhancements went into that release. If you run into any problems at all with RTP forking on a 4.0 system, Avaya will not be able to help you out.

CM 5.0 introduces official support for RTP forking, and CM 5.1 introduces support for registration without PIN.

What kind of licenses are needed for RTP forking?

With AES 4.0 we've needed an IP_API_A license for each softphone that is conferenced to a call via SSC or SO.
Are the IP_API_A licenses still required?

Regards,
Claus

Hi Joel,
We are not initiating RTP forking explicitely. We are only using VUS/RecordMessage method to record calls in server media mode (CM 4.x and AES 4.1). Can you confirm, that this type of configuration means RTP forking? If not, then how this method (VUS/RecordMessage) is working?
THX,
Gabor

Claus, IP_API_A licenses are still required for media forking. Note that in our soon to be released 4.2 release, however, we're beginning to migrate these licenses to AES rather than CM. The CM based licenses will still work, but this is not our going-forward direction.

Gabor, the way to request RTP forking is to register a DMCC phone with the following settings:
- The same extension as a "real" phone
- Dependent or Independent Mode (generally Dependent is desirable for recording)
- Client or Server media

Even though it's not referred to as "RTP forking" in the request, you have indeed requested this feature by registering in this fashion.