A communication client supporting real-time two-way voice with or within a voice communication system must meet the requirements of 6.1 and 6.3 through 6.6 that apply when communicating with or inside that system, and also the 6.2 RTT requirements that apply when it is part of a terminal able to handle text.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.