Each screen in an application is represented by an activity. Using an asynchronous message called an intent causes the system to load another activity (and another screen) to handle that type of intent. An intent that is created from a Uri causes the system to load an activity that can handle the Uri scheme. In this recipe, a Uri beginning with tel: loads an activity in the phone dialer application, and the number following the tel: prefix is automatically loaded into the dialer.

1. Create a new Xamarin.Android application. The project template will create a single activity named Activity1 (MainActivity.cs), which contains a button.

2. From the button.Click handler in MainActivity.cs, create a Uri and a dialer Intent.

3. Call StartActivity to launch the intent.

The following code sample illustrates the updated button.Click handler:

intent.button.Click += delegate {
   var uri = Android.Net.Uri.Parse ("tel:1112223333");
   var intent = new Intent (Intent.ActionDial, uri);
   StartActivity (intent);
};

In this code example, calling StartActivity and passing it the ActionDial intent launches the phone dialer app. The dialer activity in the phone dialer app is automatically loaded with the number 1112223333 when it starts - the user can view this number before pressing the Call button. The ActionCall intent is not used here because ActionCall would initiate the call directly; instead, we use the ActionDial intent so that the user can control the call from the dialer. Note that you do not have to set the CALL_PHONE permission to use the ActionDial intent.