A remote procedure call utilizes a virtual channel to allow the different components of a softphone, running on a VDI desktop, to communicate and pass voice and video data to other softphone components in the client device. These out-of-band communications.

The call-control stack (a SIP stack if using SIP signaling) communicates with the call-control server or call manager to register or establish the call.

A media engine on the client device performs the encoding and decoding of voice and video streams into native voice and video codecs and then streams the VoIP/video stream directly to the other endpoint (as directed by the call manager server), therefore setting up a peer-to-peer call and not going through the data center. This now eliminates the hairpin effect.

Currently, VMware supports solutions from Cisco, Mittal, Avaya, and Microsoft Lync 2013. We will cover the Microsoft Skype (Lync) solution in the next section.