I was able to extract few key features, which can be used in Tablet, but mostly for Phone Apps, from previous sample apps from PowerApps Group, but are not released nor mentioned in tutorial. I wish PG can include in future.
I had tried with Tel and Message from Phone Apps...great!
(Just like in Win Apps Studio).
Hope it helps and wish PG can include more explanatory notes in tutorials.
(I can see Tutorials kept updated form 28, Apr 2016, 3, May, 5, May..Thanks a lot and keep it up forthe good work.)
Kudos to PG team sincerely from me (a non-code apps creator, who only learnt from Bob Tabor on HTML5, CSS, JS and some old programming tools when I was in school , Fortran, Turbo Pascal, Cobol,..) to be part of the Cloud-first Mobile first world.
I tried "mailto:" to a group people and it works fine. But seems like "sms:" do not support multiple people. Only the first number is picked up by the iMessager. Have you tried to SMS to more than 1 people? Thanks.