One, the Android XMPP client Beem
Beem is an XMPP (jabber) client software that runs on the Android mobile platform and is compatible with standard XMPP servers and services such as Ejabberd, OpenFire, Facebook, and Gmail. Supports SASL, proxies (SOCKS4, SOCKS5, HTTP), DNS SRV, and chatting with a specific resource.
Project home: http://beem-project.com/
Second, Android chat program jchat4android
Android Jchat is a location-based chat software on an Android phone, using a peer-messaging mechanism.
Resource website: Http://code.google.com/p/jchat4android/, VoIP Client for Android phone sipdroid
Sipdroid is a SIP/VOIP client running on an Android mobile platform.
Resources website: http://sipdroid.org/
Iv. Java video calling and chat tools Jitsi
Although Jitsi is a Java video tool, it can be ported to Android.
Jitsi is an open source, secure (ZRTP encryption), high-quality SIP/XMPP video Call, conferencing, chat, desktop sharing, file transfer. Can be installed in your preferred operating system and support a variety of IM networks. Jitsi is the most functional and complete advanced communication tool. Jitsi allows you to connect to Facebook, Googletalk, XMPP, Windows Live, Yahoo!, aim and ICQ in the same software.
Resources website: https://jitsi.org/
V. Linphone open-source VoIP video Telephony
Linphone is a VoIP phone tool, currently has android\ios\windows and other versions, are open source. It allows you to query your friend's IP over the internet and call him via IP.
Resources website: http://www.linphone.org/
Android's Open source phone/Communication/im Chat project complete