In our application we have a back-to-back-connection between an operator (client) and a caller, via an ucma-application we built. Now we want to transfer the caller to another operator or number.
This transfer is attended, so we want to keep the call in the client at least until the transfer is completed.
The client application tells the ucma-application to do the transfer. As such, the server makes a transfer on the leg from ucma -> caller. In this scenario, the leg from ucma to the client application remains intact, but we want to receive information about this transfer so that we can show the transfer status in the client application. If the transfer fails, it should also be clear to the operator (it should also be on hold during the time of the transfer, and continue to be on hold even after transfer failed).
Which is the correct way to do this in UCMA?
It's hard to give you advice as there are multiple ways to do what you want depending on what you need to achieve.
I think the main problem is that you are doing the transfer in the middle, you can't tell the Lync Client to go on "hold". Because of this, you can only put the call on hold from the point of view of UMCA application. This means that if you will have to provide your own UI to unhold the call if it fails, maybe from your own Client Application GUI.
What you could do is write a Lync Client SDK controlled Lync Client application. If you have a Lync Client SDK controlled Lync Client, you could remote control the Lync Client to do the transfer, that way you get the standard Lync Client failed transfer UI. If you do this, what is the point of the UCMA application?
If you have to do it from the UCMA point of view, you could: