Lync SDK Start Audio Video Call with Send only UI Suppression mode

I am trying to build application for conferencing using Lync SDK in UI Suppression mode, the application is close to the Meet Now feature in lync so that one user will send his Video/Audio to all other users in conversation, my code is:

// Add conversation using_LyncClient.ConversationManager.AddConversation();// When Conversation added add participants// User 1 will broadcast video/audio_Conversation.AddParticipant(_LyncClient.ContactManager.GetContactByUri(user1));// User 2 and User 3 will only recieve audio video_Conversation.AddParticipant(_LyncClient.ContactManager.GetContactByUri(user2));_Conversation.AddParticipant(_LyncClient.ContactManager.GetContactByUri(user3));// Start the audio call from user1 machine
avModality.BeginConnect(AVCallback);// When recieve the call in user2, user 3 stop mic using mute_Conversation.SelfParticipant.BeginSetMute(true,(ar)=>{_Conversation.SelfParticipant.EndSetMute(ar);},_Conversation.SelfParticipant);// and same technique for video

It works but i noticed that the performance of the call is affected each time a user enters the conversation and the conversation goes to Hold then Retrive states until user is added.

How Can I start a call in one way only send (not send recive), i tried the following:

avModality.BeginConnect(AVCallback,ChannelState.Send);

but it didn't work, also i have a look on the Conversation Properties, Moadilty Properties but nothing looks helpful.

the only thing i found related is avModality.AudioChannel.State but i can't find a way to set this property?