The BackToBackCall class is staple of more complex UCMA applications, especially those that perform some kind of third-party call control (brokering or providing services to calls between other users). In a nutshell, the BackToBackCall class allows a UCMA-controlled endpoint to keep a handle to a call that is going on between two other endpoints, rather than between a single remote endpoint and the UCMA application. But there are several features of the BackToBackCall class that you may not be aware of, that can be helpful in certain situations. Continue reading “Advanced BackToBackCall features” »
Lync uses a number of different protocols to operate, and it can sometimes be confusing keeping track of which one does what. This is a short overview of the protocols in Lync and what they are for. Continue reading “Protocols used by Lync” »
If your application handles audio calls with users, you may need to be notified when one of those users places the call on hold. It’s relatively easy to get these notifications in UCMA, but it can be a bit counterintuitive, because there is no event anywhere called HoldStateChanged or anything like that. Continue reading “How to tell if a call is put on hold in UCMA” »
Based on some recent experiences, I wanted to write up a quick summary of how the UCMA runtime handles incoming SIP messages, which is somewhat different from how it works with the Lync client. Continue reading “How UCMA handles incoming messages” »
When calls come in to Lync from the PSTN, Lync normalizes the called phone number by applying the normalization rules from the global dial plan. However, if the number starts with a plus sign (+) when it arrives from the gateway, Lync assumes it is already correctly normalized in E.164 format and skips the normalization step. This means that there’s no way to apply further rules to the called number when it is already formatted with a plus sign by the gateway.
As it often does, the Lync Server SDK comes to the rescue here with a slightly complicated but functional way to remove that plus sign and get Lync to apply the normalization rules to those calls. Continue reading “Removing the plus sign on incoming PSTN calls” »
This is one of those random things in UCMA that you almost never have to use under normal circumstances, but in that one very unusual case where you do have to use it, it can be very frustrating trying to figure out how it works in the API. Continue reading “Sending INFO messages (or other messages) with UCMA” »
A while ago, in a post about how “manual audio routes” work behind the scenes, I mentioned I was planning to see if it was possible to set manual audio routes for endpoints other than the “local” endpoint for the call, by sending INFO messages manually to the audio/video MCU. In other words, can I join a conference from my UCMA application as a trusted participant, and then send manually constructed INFO messages to create a manual audio route between two other participants in the conference? Continue reading “Third-party manual audio routes: not possible” »