Q: Android VoIP call implementation First of all I'm a newbie in VoIP implementation. I need to implement VoIP single and group call in android application. Could you tell me, what is actually the best way to achieve this ? I'm looking for Android SIP library (probably open source) which should:


*

*has good documentation with simple app examples

*be ready to use with java


Maybe just native android SIP api will be the best ? But I heard that it doesn't support group calls.

A: Most of the voip libraries use C/C++ implementation for various reasons. You can use PJSip which is a C voip/sip stack. It has a good documentation but you have to build it yourself using android ndk . It has good documentation and also contains processes to build it for Android and other platforms. But there is no java/android wrapping built in so you should do that yourself. Another option is Liblinphone which is also based on C stack but provides all of the wrapping and implementations out of the box so you don't have to bother so much on native codes. It also has a sample application which you can try yourself. One downside of Liblinphone is that it lacks proper documentation and you have to dig in more. 
Regarding the android SIP api, I don't think it is a good option as it has much more limitation and hardly maintained. It is based on Jainsip stack which is a 100% java stack but is too verbose. I personally would like to recomment Liblinphone as I am currently implementing it and am pretty satisfied with it. Best of luck...
Update
Here is the source code of linphone for android if you are interested in it. You can get pretty much idea of Liblinphone for android from it. You have to dig much more into the sources though.

A: You can have a look at Restcomm Android SDK:


*

*It's open source, with an active community around it

*It using SIP for signaling and Webrtc for media so should work nicely with NATs, etc

*Comes with 2 sample applications that you can play with and alter their code to experiment

*Comes with quick start guide, reference doc

*You can check the Olympus sample App right away by installing the .apk from this link


Notice that the SDK doesn't support group calling out of the box, but you could combine it with Restcomm-Connect open source platform to add such functionality very easily. Restcomm-Connect also comes with docker, so you should be able to install it right away.
Please let me know if you have any questions
Best regards,
Antonis
