It does it on a iPhone or iPad, both of which have Roger installed. Since it is an over the internet kind of connection, yes, it will do it when not on the home network, like on cell data, a hotspot, another Wi-Fi network,etc.
The Echos at home say/do nothing. It is like having another Alexa in my mobile devices. My phone IS a stripped down Alexa device with Roger installed. It's basically the speaking features of Alexa, like news, sports, weather, traffic, etc. I was told by Ricardo they are working with Amazon to add more features.