UCMA 4 - GetRemoteParticipantEndpoints() issue on iOs clients

In my application at certain point i need to make an MCU dial out and consequently be able to understand if the callee actually get into the conference.

here is the code (the interesting part at least..)

//....
ActiveConferenceSession.AudioVideoMcuSession.BeginDialOut(AgentCalled.SipUri.Address.Uri, AgentDialed, null);
//....

private void AgentDialed(IAsyncResult ar)
        {
            if (ar.IsCompleted)
            {
                IEnumerable<ParticipantEndpoint> agents = ActiveConferenceSession.GetRemoteParticipantEndpoints().Where(pe => pe.Participant.Uri == AgentCalled.SipUri.Address.Uri);
                if (agents.Count() == 1)
                {
                    // Works fine except for iPad and iPhone clients
                    //....
                }
                else
                {
                    //....
                }
            }
            else
            {
                //.....
            }
        }

It works fine, but if the callee is using an iOS client he is able to answer to the incoming call made by the MCU dial out but "agents" will always be 0 in count.

Ps Despite on other problems, just for a test i tried ConferenceInvitation .. begindeliver... but the matter doesn't change at all.

Any help will be appreciated.

Cecco