Questions for VoIP app development (SIP etc.)

Question

I am looking for general advice (technologies, best practice etc.) regarding the development of a VoIP application for Android. Similar questions have been posted, but I included specific questions.

I did quite some research and I noticed that there are several possible solutions (of course I know about the SIP stack in the SDK (also that it includes even voice transmission), but since it's not available on most devices, I don't intend to use it. Also, I read about Adobe Flex implementations but I would like to stick to something native).

What stuck to my mind is the following:

• initiate the session using SIP (the server exists). Use SDP in the messages to discribe the session.

• establish p2p connection (firewalls/routing may be a problem - STUN could be used - DNS may be involced than)

• make actual transmission, I believe that the packets/procols involved are (payload) in -> RTP in -> UDP in -> IP.

This seems quite complicated at the moment so my first question is:

1)is this a standard approach? Is it best practice? I got some hints that, instead, MSRP could be used to transmit content, but I have read that it is only for IM, files etc.

2) Which SIP stack should I use for the best results/performance? I can use Java/Eclipse for development. I was thiking to choose JSIP (or tinysip, based on jsip) but am not sure.

3) Please give me a few hints about how to implement the data transmission in Java for Android (RTP)

As a last note, I am not excluding at all pjsip. I am thinking that it may be actually faster since it uses the NDK (I could switch to C++, np) . I also read that it already includes audio/video transmission. I just don't know how easy it is to use and extend it and how good it really is. If you have used it, please let me know!

Thank you.

PS: Although not urgent or certain, portability may be an important factor for future. I will need video transmission as well in the near future.

Answer 1

You should check out the IMSDROID project. It uses Doubango Framework which is written in C and is highly portable. What more, it is open sourced too so you can play around with their code and possibly contribute towards the community.

http://code.google.com/p/imsdroid/

cheers :)

Answer 2

Take a look at teamSpeak. They provide native sdk-s. But they aren't free. It's not P2P, requires a server (at least as I know) May worth a minute. http://www.teamspeak.com/?page=teamspeak3sdk

Answer 3

Writing your own SIP stack takes a few months with only basic features. I would recommend to use an existing sip stack. There are a few opensource discussed here .