Is it possible to allow a user to (after pushing a button) call a specific number?

I'm making an app using apparchitect and I would like to know how to use JavaScript to call a number. I have tried using different ones already uploaded to no avail. Is it possible to allow a user to (after pushing a button) call a specific number?

In the simplified app maker I can use javascript if they do not have the function I want. This is for an iphone app. Please help this app is really important. Thank you.