I am developing an application for Android. For this task I use Adobe Flash Builder and an SDK. I found a page that deals with this topic in details. The page (if you are interested: http://www.voip-sip-sdk.com/p_456-vo...tion-voip.html) also provides code snippets that handle the physical buttons and the rotation features of the mobile devices. I am a beginner developer and found the information really useful. I hope others who would like to develop an own application will find this information valuable.