I’ve tested and tested and can’t get these commands to work

Latest iOS (11.4). Siri always assumes when it hears the word ‘room’ that I want to control something in a connected Home

Having tried everything, with both the WebEx app closed and backgrounded, the only Siri command that I can make work with WebEx is the simple, ‘Hey Siri - open WebEx’

I would appreciate some assistance or some clear detail on what these commands actually are to enter your PMR and utilise autocallback using voice (Siri) alone

Thanks.....: Samuel