I have implemented voice commands in my Windows Phone 8.1 app, but I have run into 2 problems. The first problem, is that I would like to have the command execute without the app opening. I know it has to load the app to execute, but I'd like it to not be visible, or at least disappear when it is done. The voice command just causes a REST call to be executed and has no UI updating in the process. How can I make it not open/render the view?
Like you stated, it is not really possible.
You could instantly close the app and handle your request in the Suspension event handler using the referral.
But: You will still get the splash screen and is will probably be confusing for the user (why does that thing pop up?). Also, you cannot be sure how much time your suspension gets and if you are on a bad network connection, your rest call may fail.
It might be better to just show a confirmation/progress screen and have the user tab out himself.
Also: Be careful with sayings like just a REST call. If you are on a bad 2G connection or have some other network activity running, even a few kilobytes can take up some time.