There is no way to start a Teams call from the Teams phone with multiple parties selected.
Instead, you will start a call with one party, and then add in as many others as you would like
To add another party to the ongoing call, select the people icon in the top right
Press the "Add people" button
Type the name of number of the person you want to add
With everyone added select the check mark in the top right
This will bring you to a window showing everyone who is being added, press tap to return to call to return to the normal call screen
