In this paper, I present the proposal of a virtual reality subjective experiment to be performed at Texas State University, which is part of the VQEG-IMG test plan for the definition of a new recommendation for subjective assessment of eXtended Reality (XR) communications (work item ITU-T P.IXC). More specifically, I discuss the challenges of estimating the user quality of experience (QoE) for immersive applications and detail the VQEG-IMG test plan tasks for XR subjective QoE assessment. I also describe the experimental choices of the audio-visual experiment to be performed at Texas State University, which has the goal of comparing two possible scenarios for teleconference meetings: a virtual reality representation and a realistic representation.