how to create application that always run in the background?
<p>I want to create an application that listen to sms and always run in the background. </p>

<p>The service must start when the user turn his android on - and always in action until the android device is down. </p>

<p>I know only how to create application with GUI ( with activity ) - but on this case i don't want to have any GUI with it. </p>

<p>I don't find any example of how to do it. </p>