yaxim - Yet Another XMPP Instant Messenger
yaxim (Yet Another XMPP Instant Messenger) is a Jabber/XMPP client with open source (GPLv2). Why pay for SMS if you can have unlimited messaging on your data plan?
yaxim aims at security, low overhead and keeping your server connection open. So far, it only supports a single account.
Yaxim is Open-Source. You can contribute too!