How can I make a point-to-point VoIP call over Wi-Fi? I am searching for a way to make a point-to-point VoIP call between two Android devices without having any intermediate server (SIP server) or an Internet connection. I just have an access point (or multiple access point connect via LAN) and I want to make VoIP calls over Wi-Fi only. Is this possible?
You can use CSipSimple to add a local SIP account on both phones without having the need for an intermediate SIP proxy (or server).

Add a general 'Local' account. You only have to provide a SIP username for it.

When that is done on both phones you can call the other phone:


You have to know the IP address or dns name of the other phone
You need to know the just set up SIP username of the other phone
Dial 'SIPusername@IP-address' to call the other phone
You need to switch from the initially shown number pad to the extended 'SIP uri' input window  


Click on the green marked spot in the left image to navigate to the SIP input activity :