how to setup voice chat over wifi and 3G network?

I wanted to add a voice chat featu开发者_运维知识库re to my business app. I have been trying hard to find anything useful but there is not much help regarding this. Could anyone plz point me to something concrete??

PS: The skype app makes use of this feature.

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This is a lot of work as there is no "built in" sdk features or third party off the self components that will help you do it without a lot of work on your end. Your options (as far as I know) are:

• Build your own solution.
• Look for a third party solution.
• Look for a open source solution.

Voice "chat" could be one of many things like:

• using the voice features of a cellular network to a conference call.
• using the voice features of a cellular network with a PBX server that supports conference calls.
• using a VOIP solution using a SIP stack with a SIP server
• using a XMPP Jingle solution (I believe the google voice service uses this)
• using your own SIP setup solution
• custom solution

None of these options are easy.

Open Source SIP implementations that have iphone ports (that I know of):

• reSIProcate
• pjsip

Update:

SIP & Jingle both use RTP for the actual transport protocol between the parties. RTP is a UDP point-to-point protocol. The ports which form a session are negotiated using other protocols such as RTSP (using SDP in the setup method) and SIP. RTP and RTCP typically use unprivileged UDP ports (1024 to 65535).

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For easy Server / Client setup check Jingle Nodes in combination with SIP Communicator which is a Desktop application. But as being opensource I presume you can reuse a lot of the code to make it mobile. Specially for Android. Check this draft of a Jingle Nodes Setup Guide