Android Audio/Video Calling
<p>I know this is some sort of pattern question and had lots of reviews but I am here for something slightly different. In the world generally there are 3 main types of APIS which provide these functions:  </p>

<p><strong>QuickBlox, Sinch and PubNub</strong>.</p>

<p>I do not want use any of them. They are purely horrible for me. Now each of them separately.</p>

<p>1) <strong>QuickBlox</strong> - Setting its API is already a huge headache, you are writing heaps of code, logging user every time to get the calling ready. Plus QuickBlox do not keep any session out of box (in the background) so no luck with background listening for incoming calls. So I quit QuickBlox.</p>

<p>2) <strong>PubNub</strong> - Pretty much OK but the price and the trial is absolutely crazy. I can't imagine myself giving someone 50 dollars every month just for audio call and video call functions, whereas I would not have any income from both of them as there is no such good app in world which offers paid app-to-app calling, so mine should be free too. And also I am in the development phase so I do not want to waste money. They say they giving free 100 users at start. But what it is ridicioulus as 100 users won't give any income so the PubNub is fast out.</p>

<p>3) <strong>Sinch</strong> - This was the only library I loved and loved really much, I even asked them to add a function of WebRTC of videocalling and they did it! But still there is one more big issue which cannot be handled. The background service. Sinch does not provide and you do not have any chances to listen for incoming calls if your app is killed, so Sinch unfortunately is out too.</p>

<p>4) The last option I HAD to do, because I had no choice, was SIP of Android. It is basically saving hugely but I encountered an issue. I generally and now think to fully move to SIP calls, I did try to load the demo, but what is the issue, is that as far as I understood, to make SIP calls you MUST have a SIP account pre-registered. The horrible part is that I am developing a chat application and that chat application should have that audio calling at least. So it is not good practice to ask users to register a SIP account with in-app account. So by Googling I did not find any solution and came here to ask. Is there any way,to register to a SIP server (free SIP servers which are plenty on the net) with default SIP class of Android, without forcing the user to do it manually? If yes can you please provide code?</p>