I want to develop an app in android that make internal calls within an organization. Like we have landlines extension same way i would like to create app in android. I done some research and get to know about SIP/VoIP in Android 9+ API. But I am not able to find any good resources for it. There are some projects like sipdroid, linphone etc but not able to find resources to integrate them with android and create a basic app. Also I came to know that I have to register my extension with some provider.
So anybody who has good idea on SIP/Voip please kindly suggest me some checkpoints and resources.
you can download linphone libraries from http://www.linphone.org/eng/documentation/dev/